Buggering each other in the butt is just going to make a stinky mess ... not a baby.
So let them marry “fecund women trolling for ‘surrogacy’ opportunities”.
...I see the point of my post completely eluded you...
...but you certainly do see, I’m sure, that these two, or any other like couple, can ‘naturally have’ all the children they wish, just by paying women to carry the child to term...they can go ‘forth and multiply’ the same way anyone else does, completely apart from whether they bugger each other or not...
...they can ‘marry’ each other, be completely chaste, and have natural children...all of which becomes a business opportunity with the mainstreaming of the surrogacy line of work...