I also agree with Joshy in that having a child with Bob wouldnt neccessarily mean that Mila loves Bob more than Paul or vice versa. But i just cant see Paul agreeing to it.
There probably needs to be a scene where the three sit down and discuss the possibility and wish of having children and how to handle that kind of thing with their throuple relationship since Mila cant be pregnant with both their childs at the same time. But that would be a far out in the future thing, after the throuple thing is far more well etablished than it currently is in the route, definitely after the three had threesomes and much experimenting with that.
Or you could play it as a accident baby, which personally seems suspect cause Mila clearly is on contraceptives- the risk isnt brought up at all, Paul clearly creampies Mila on the regular before all of this and Mila doesnt even consider it when finally having sex with Bob. Whatever shes on, its clearly extremely reliable.
So for me if Mila has a baby with bob at any stage be it the first or the fifth it's going to change her and Paul's dynamic massively
Probably the biggest change will be living situations so if Mila has bobs child (for the sake of argument we will say it's milas first child) and Paul's not wanting to raise it who does she stay living with? In my head I would say she moves in with bob after he is the dad so then Paul will at some stage become an after thought , but then even if Mila and Paul already have children and they let bob have a child with Mila the living dynamic would still likely change with bob likely moving in with Paul and Mila
I suppose one way around it is that Paul has issues in that area so they go to a sperm bank and the donor they picked happened to be bob and they weren't aware at the time
I guess for me as it only seems to be that any potential pregnancy seems to be with bob and hasn't been suggested in any other route it feels like a wolf in sheep's clothing ( NTR covered with the premise of NTS) as like you've mentioned I just don't see Paul agreeing to it
For me with Bobs route anything outside of Mila and bob having casual sex or Mila ,Bob and Paul having threesomes starts to shift the power dynamic of the sharing relationship more in bobs favour eg: with the road map it has bob taking Mila to Paris and sharing Mila with his friends , so it then starts to give the impression that bob is the primary partner in the situation and even if that isn't the case where does Paul fit in to it
Well enough from me that's my thoughts on the matter