One potential hot topic that many multiples will find helpful to put on their agenda for one or more meetings is the topic of gender identity and sexual orientation -- especially if you have residents who are a different gender than your body. I call these residents "cross-gendered residents" for lack of a better term for them. Their gender is different than your body. These residents may have sexual desires and attractions that pose a problem on one level or another for your system or for your social environment.
This is a very common issue for multiples. Short of every resident whose gender does not match the body being asexual, their attractions can cause disagreements on behavior and potentially challenging sexual-attraction issues.
These challenges can compromise your system in social settings, romantically, cause marital issues, or cause internal conflicts for your system.
In many cases, when with a partner with a strong gender-preference, it may cause problems being truly deeply intimate because your partner may or may not know the perceived gender of the person they're having a relationship with at any given moment. Some people can get around it, others cannot.
It is up to your system to work out how these different potential relationship types do or do not affect your system. You may have some residents who are apathetic to this issue, others who are adamantly opposed to certain types of interactions, and it may or may not be fair to your differently-attracted or otherwise-gendered residents to impose restrictions on their behavior when you aren't imposing restrictions on everyone equally.
Note that residents who are restricted without their permission are more likely to act out against the house rules. You may need to find ways to get their agreement if your system decides that certain activities (dress, accessories, lovers…) would violate the group's rules. To avoid any internal conflicts, these decisions should be addressed by the group as a whole. Systems get along better when everyone possible participates in making the rules.
On a general FYI, if you find that your system cannot make up their mind on a single physical person to be attracted to, and you're going to act on attractions to separate physical people in one way or another, you may want to look into polyamory, which is advocacy for responsible non-monogamy.