Honestly?
You have three snakes in one tank and don't seem sure of the sexes - splitting them all up is pretty much the best advice anyone can give you.
Your best bet would be to set all three up in tubs in fairly simple surroundings (two hides and a waterbowl on a paper substrate ) until you get a reliable sexing done and they are all eating fairly consistently and doing well.
Then you can think about whether you are set up to breed and if the female is ready as well in terms of weight, age and condition.
But housing them seperately is the way forward in any case - I used to have multiple BP's in a 5' x2' x2' wooden viv and though they were doing fine.
I moved them to a rack system housed individually and they really are doing far better in ways I just wouldn't have thought. I argued like heck about it when I first came here.
dr del