There has been a lot of heated debate on "Old Guard". If you missed it, congrats! you’re not bothered with politics and had fun. If you didn't, I’ll probably be saying nothing new. But to summarize; the topic "Old Guard" refers to a glorious past where everything was simple, codified and organized. The gist of the myth is that there was a widespread organization led by "elders" to which you were invited into. Through several initiations and badges of merit one would climb the ranks, to basically become a desired play-partner. The details vary from person to person. Some say all dominants had to start as submissives, others say you as a dominant you had to display a certain level of skill to become a Master. For submissives there were also tests before the honor was bestowed to be allowed to wear the hanky-code of that particular kink.
"Old Guard" never existed. There are enough articles on the web that point out why it can't have been and why some people still insist it did (for less than honorable reasons). But every persistent myth has a kernel of truth (or desire).
However, Some people live by the principles of what they see as “Old Guard”. This is fine as a type of playing/living or guidelines for behavior but do not make the mistake that this was ever the norm or has historical roots.
I'm sure there were groups in the past that had codified conduct and to which you had to be invited, but i would be surprised if those groups had more than 10 core-members. You can observe the same thing in the various "Families" or "Houses" that exist today. ( FYI, i myself belong to a Family) Typically, these originate around 2-3 people that have an intense relationship and who are all into (the same) kink, and can develop into families with many more members.
This seed could be a couple ( or ménage-a-trois) that live together in a BDSM relationship where gradually new members (play-partners) are introduced. Or some people just like to hang out together, like a clique in high-school, and have no problem playing in each other’s presence. Eventually play-partners will we swapped, passed around and shared until someone realizes "We just like a leather house/family". Through bonds of friendship, caring, support or fetish compatibility this family can expand but I would think most families die or fade when the founders drop out of view, effectively disintegrating the core.
Like barbaric tribes, a family will have rituals. Mostly to mark an event, like the admission of a new family member. Since it's a special occasion, you want to make something special out of it. A budding ritual in my family is, when a new member is accepted, all existing members give a little something in relation to the new member's role. in one case a steel chain, the lock and it's keys were given to a new submissive by different family members. So when the sub was collared, he actually wore a composite gift from the whole family. Other rituals can be used to mark a temporary change, like the donning of the sub's collar before a play-session. Many protocols can be ritualistic in nature of course.
Being in a BDSM Family, one can assume that all families have a hierarchy but i think the implications of that hierarchy will widely differ. (what is your relation to the submissive of your submissive?) To complicate matters, non-kink relations can intersect the family-hierarchy in odd ways. ("my boyfriend's slave is the boyfriend of my master") But, obvious as it may be, The rules of the hierarchy are designed to be comfortable and/or stimulating for the participants. so, if you don’t really like your master's master, there will probably be a rule that limits that interaction. Any existing rules can always be amended.
The extent of protocol in a family is also based on the need of its members, usually just enough to be fun for the members of the family. If you like your protocols, your family probably will have a lot of them. Whether to give clarity in what's expected, predictability, the excuse to punish, the game of finding loop-holes or the frustration of being severely limited in your expressions; i dare say that there are always some protocols or rules in place to ensure play-partners keep in sync with each other. This could be the order to call every evening and report on your day, or the knowledge Master wants to be informed if anything is upsetting you. Families without such syncing/adjustment mechanisms won’t survive long.
Being in a family, like being in a long term BDSM relationship, gives the play-partners the opportunity to move beyond the "slap and tickle" that is normally played with near-strangers. As trust, familiarity and understanding of each other builds, the play can become more and more hard-core or fine-tuned. It will also give the members the experience/confidence to play harder with outsiders or to clearly define their limits. But being comfortable with each other usually results in the kinds of play other people stare at. That is, if you play publically; which seems more common, or more noticeable, in families/houses. That might be because if you go out as a family; the family gives you the confidence to do stuff you wouldn't do if there's just 2 of you and it supplies more bodies for expansive play-scenes.
I want to emphasize the point of hard-core play being fine-tuned. It may not be obvious or even noticeable but a Dom will know, by virtue of knowing his sub, which actions (not) to do in order to continue the scene. It looks a lot more random from the outside than it actually is. And what might appear to be an all-you-can-beat, usually is an intricate dance between Dom and Sub.
Make no mistake, Families and Houses ARE intimidating to outsiders. Suddenly you're not dealing with that cute sub/hot Dom you'd like to play with, but a whole bunch of people. Most likely with people mixed in who you have seen or will see play hardcore. And there may be permission involved. Or that Dom who's playing with not one but TWO or THREE Subs ( the words sub and Dom are interchangeable here), must really be something to pull that off. And since a family has their little rituals/protocols; the leap to Old Guard is easily made. Especially if you happen to see two families on friendly terms with each other.
tips & tricks:
If you want to expand your family with a new member, make sure there is a sufficient personal relation to build upon. Being part of a family includes emotional and non-kink care, so a fantastic play-partner with annoying vanilla habits probably isn’t a good addition.
If you are invited into a family, always realize that it’s like getting a new set of in-laws (possibly with benefits). You will need to connect to more than just your play-partner and the family as a whole should feel like an asset to your life, not a footnote.