So I see this is a really... extensive... thread and I eventually found the RX3 update. I've mostly just been messing around with the free H mode, but I noticed that while the mods do enable futa stuff, scene wise it seems impossible to have two futas going at it while being able to impregnate each other.
Males have basically 0 personality customization (which, fair, but also I feel like there's gotta be an option for female led stuff), but this means that if you turn them into a girl by changing their body there's no preg option stuff (since it's found in the <3 tab with other personality/traits). Men also can't seem to be penetrated from what I've seen so there is no option for a futa made this way to be on the receiving end.
Women can fit the fetish easily enough, but due to being unable to play with the guys like you can the girls there seems to be no way to swap places. Also, aside from changing location, "Lesbian" is basically just a cutscene as you don't take the role of either character and you just watch them (which... might be how it is in the story as well?).
I realize that this goes into "missing the point of the game/be happy with the mods available", but is there any way to do like... any of the options? There's no way to play with the guy, there's no way to participate during the lesbian thing? I definitely realize that adding male pregnancy involves a lot of wonkiness and isn't planned at all for a lot of reasons (don't know if the futa mod is from the same person as the pregnancy mod and it just gets weird), it just seems like a bummer that you can't have two characters who are able to swap places/penetrate each other without doing insanely convoluted stuff like creating both of them as a male/female the hard way.
*also it is as I type this that I realize just how odd I sound, sadly fetishes are fetishes
No, men cannot be penetrated because only the PC can penetrate and the only man in the game is the PC unless you use Kplug, which allows background "buddy" characters to join in with a second girl completely separate from you in H scenes. You can join two girls who are in the middle of lesbian H, provided you successfully get close enough, by peeping and then pressing the blue icon in the bottom left. This requires they are both lovers and at least experienced if I remember correctly and it starts a threesome. This is the only way to start a threesome without the Kplug mod, which allows for girls who are in the room when you start H to automatically join as background characters that can engage in lesbian H with other background girls, can be swapped with the girl you started H with, and this is where the buddies can be summoned with the invitation menu for vanilla sex in the background. You can also do the same, hitting the blue button, for a masturbating girl if you can reach her before she finishes or discovers you are there and runs if she isn't in the horny state. Because Lesbian H is the one time where the girls will not start if they are not alone in the room and will run regardless of horny state, the only way to get the background girls or buddies is to use the invitation menu. The same applies if no other girl is in the room except the girl you start H with. As for futa, you can fuck them like any other girl as long as they are a girl character card with a penis applied. Yes, you can attach a penis using the maker regardless of whether you are in the male maker or not. Yes, futas based on female cards CAN get pregnant, however, it may not look right as the penis may clip into the belly once it gets big enough. Also, males have zero personality customization because they were never meant to be computer controlled. Females can lead in some positions that can be considered dominant for the person being penetrated, such as cowgirl. There will be a button above the box in the bottom right during H that specifically says girl leads and this will have them controlling when they start, whether they use the alternate mode in the current position, how fast they go, and I think they can switch positions as long as it is in the same category. Actually, you are incorrect about having two futas going at it, though only one will be able to impregnate. To do this, create a girl card you wish to make a futa capable of penetrating, then drag the card from the folder onto the game window while you have the male maker open. It will copy the girl into the maker, where you can save the character as a male card and play as them. This can also be done by placing ANY card in a folder marked kfuta if you have the Kplug mod and then pressing F in game to turn on futa mode. Oh, and the invitation menu in Kplug is opened with the I key. In the final period of each day or on Saturdays, you can also use the invitation menu to invite other girls during H. This is useful when you want a second girl to join in, but none were in the room when you started, and can also be used to invite girls that aren't registered in the class roster. The girls that are invited this way, like buddies, are background only except if you drag and drop them onto the green attach points. You can move the girl by holding ctrl and can see the attach points by holding shift, I believe. They will otherwise remain in the background and join with any other background girl or buddy in range once you get started with the girl you started with. Buddies are not only guys, either. You can have futa buddies, which can penetrate as they are guy cards, just not the PC or the girl you started H with since they are background only.