Look into the cost of a spay so you know what you are dealing with, and save what you can toward it so that in a few months, or Jan you will be able to get one ...... my vet charges approx $230 but an exotic vet 6 hrs away from me charges $85, ..... prices can range from hundreds of dollars to much more affordable levels, depending on the vet and where you are. Of course the most important thing is making sure you have a good vet that can safely spay a rat
It is great that you have created a safe play area on the bed for your boys. Re rats sitting on you ...... some will, but definitely not usual behaviour for rats to do it for long, especially for young active rats, because rats need to get out in a safe play area (in their groups not one at a time) and run and play and climb and explore and interact with you for one to two hours per day ........ I find that my rats like having access to their cage when they are out playing and they tend to go back and forth. Although some rats seem to be ok, is normal for rats to be afraid if there are predators, like cats, in the house.
So nice that they boys were parenting the baby
Btw, as you may be aware, it is dangerous to mix rats with any other species because rats are either predators (smaller animals) or prey.
good luck with dividing the cage. It is a good size and they should have lots of room if the space is use wisely. For example, a critter nation cage also has a base that is 3 feet by 2 feet as well as height, and when divided in half with the space used wisely, it can house several rats comfortably in each half.