Will we be able to marry mom/sf/f/bro or sister and have them move into the mansion at some point in the future?
Mom, never, you will not be able to get into any illicit relationship with her, as it's against her character.
Brother, sister or dad, you may be able to move in with them, at some point depending on the devs, but marry? No, there are in-game laws against that.
Step-Dad, depending on the devs, possibly at some point, if you have already ruined his marriage with your mom by having his kid, but it would be a long way off.
Not sure who you are asking about with 'f'. If you are asking about a general Female, I don't think Russian law allows 2 women to marry, but move in with, yes at some point.
Dog, there are real world laws against that, meaning that the x-rated dog content was removed from the game long ago and the mods have been removed (and must not be linked to on most platforms so if you have them not do it here, on TFgames or the GL Discord) to stop the servers being taken down. As for having a dog as a normal pet in-game, I think you already can.