UPDATE
It's now been 3 months since I adopted the two new girls and things have, unfortunately, not improved in the least. Last night was the last straw when sigma, the rat that seamed to have a good relationship with me, bit my hand in a nasty, aggressive and unprovoked way. The day before her sister bit my thumb and began to chase my feet as I was trying to get to a tissue. Both have now bitten me and others on multiple occasions, and it's just becoming too much for me to handle. Every day they seam to become more aggressive towards me and the other people in my house, and it's not lack of confidence or trust in me. I had to deal with that with my rat Nifti, and she never chased me or tried to bite harder when I was pulling my hand away.
This two rats most probably have hormonal issues, but unfortunately I do not have the funds to spay both of them. And even if I could find the money, the time required to reeducate them is time that I do not have at this point in my life... Also my older girl is now 2 years an one month, so time is prescius with her.
Given all of this, I decided that most probably the best thing to do for everyone is to give the rats to someone with more experience, that knows how to deal with such character problems, as I can see that all the rats involved are no longer happy with the situation (all are territorial, scratching and rubbing themselves on every surface they find). It is not a decision I take lightly, I've been going back and forth for a few weeks on this, trying all kinds of methods to make things work.
Sorry for the long message, I just needed to write it all down, and this forum has always helped me to get a clearer picture of what could be the best thing to do. If you have any advice or even just observations, feel free to respond. I'd like to know how other people have dealt with similar situations.
For now, thanks for reading