Opinions needed - what to do?

This isn't 18+ in the material, but I need some good 18+ (i.e. adult) opinions and feedback - I'm afraid that if I post this in the regular general discussion forum, I'll get a lot of unhelpful responses. :/ Anyway, here goes:

I currently have two rats - Petyr and Renly. Petyr was adopted first, then I bought Renly from a breeder to be Petyr's buddy. They got along for two weeks after proper intros, and then after those two weeks Renly got super aggressive to Petyr. I had both neutered to ease the hormones and tried intros again, but Renly still wants nothing to do with Petyr. He shows all the classic signs of aggression and dominance and when he's not being aggressive, he's mounting Petyr or pinning Petyr or peeing all over Petyr's head (which I only discovered after giving Pete a kiss on the head after their play time - yuck). >:[

Since they're neutered, I'm able to adopt female pals for them because rats need company and since Renly won't be nice, they're currently lone ratties and I can tell that Petyr is sad (Renly doesn't seem to mind, but I'm not sure how to tell for sure xD). I found three females up for adoption relatively close to me, and I'm definitely applying to adopt the mother (named Lily - but I'll probably rename her Catelyn). Here's where my question comes in....

I'm not sure what to do, and I'm stressing myself by out worrying about what would be best. I can adopt just Lily, or I can adopt Lily and her two daughters. If I adopt Lily, I'll introduce her to Petyr, but that will leave Renly all alone (though I wonder if he's happier this way? He's kind of...manic :/). If I adopt all of them, I'll have 5 rats - more than I'd planned to have at one time (at least, more than I'd planned to have at this time). I'd be comfortable at 4, but I don't want to adopt Lily and one of her daughters and leave the other one alone at the rescue - that just wouldn't be fair. The rescue suspects that Lily may be pregnant (huge "if" right now - they should know for sure next week). If she is pregnant, they'd obviously keep her till her babies were weaned and could be adopted. I think the best solution for me, if this is the case, is to adopt Lily and one of her female babies. That way I'll have 4 rats - two females - and can introduce one to each of my boys. And if Renly, for some reason, refuses to accept the baby girl, I can introduce her to her mama and Petyr.

Most of my concern doesn't have to do with the rats themselves, though - I'm pretty sure I'd be able to handle having 4 or 5 rats once they're all introduced and together. I recently adopted a Greyhound and, while I earn enough to care for Eli and my rats, I don't want to put a huge stress on myself. I've got a small but growing vet fund, so I can cover routine care and emergency care for the rats (Eli has insurance in case of emergencies - yes, I'm one of those people xD). I work my butt off so that I can afford the best for these furry critters that make my anxiety less bad and keep me company and are a "replacement" for siblings and nearby friends that I can actually go hang out with in person - I have two of these friends: one's starting college next year (they grow up so fast xD) and the other is starting grad school in New York - really far away. The rest of my friends are online friends and are states away... But anyways, back to the point...

On the one hand, it would be easier for me to adopt just Lily and introduce her to Petyr. Then I could think about getting her spayed to reduce the risk of mammary tumors, female-related ailments, etc, and could later (a month or so after Lily's settled in) focus on finding a girlfriend for Renly. This, to me, is ideal - I'll only have to worry about one introduction at a time and won't be too stressed with the sudden doubling of my number of rats. The only problem with adding a female later is the possibility that Renly won't like her, and that Pete and Lily won't like her either. Then what do I do?

On the other hand, I could adopt all three and not get them spayed (or do it at intervals as I build back up my vet fund), and I would maybe have a friend for Renly - if he could get over himself and his nuttiness long enough to realize that the other rat is actually okay. If Renly can't get over himself, I could introduce the daughters into Lily and Pete's group and they'd likely be okay. The rescue tells me that Lily and her daughters get along beautifully and no one displays dominant or aggressive behavior - a definite plus.

And yet, if Lily is pregnant, I could adopt her and one of her female babies, introduce her to Petyr and the baby to Renly, and then only have 4 rats. If Renly doesn't want to be friends, I could introduce Lily and Petyr to the baby.

Cage space isn't a problem - I have a double Critter Nation and only two rats - a DCN can hold like 12, if I'm not mistaken, so I've got plenty of space xD

So, does anyone have suggestions? Either opinions on what I should do, or maybe some way of making decisions that would be helpful? I tried a pros-and-cons list, but it came out even and I was able to overlook almost all of the cons I had listed for all cases. I honestly don't have a preferred outcome - I just want to do what's best for the rats up for adoption and for my own two rats.

... Part of me thinks that I'm worrying way too much about this. Initially, I was going to adopt all three. Then my parents were like "Are you sure?" and suddenly, no, I'm no longer sure.

Help? o.o

ETA: So sorry for the novel-thread - I'm just really obsessing over making the right decision >.<