Introducing adult cats, please help!

Hey everyone! i wasnt sure where to post this, hope im in the right place. So i recently split with my partner of 7 years. We had 3 cats, 2 female and 1 male, they are from the same litter and have always lived together (they are 7). Anyway i have moved back in to my parents house, they have 2 cats a female and a male. They are both about 6 or 7 to. The problem is im wanting to move my cats in here with me. We have plenty of room, i have a loft that i use as like my own sitting room and this is where my cats will be based (there beds and litter tray etc will be up there) and my mums cats wont be allowed up there (they are mostly kept downstairs). They are all nice natured cats but im not sure how they will react when they have to live together. Can anyone offer me any advice on how to handle this situation? Am i letting myself in for months of fighting and turmoil? Any advice would be much appreciated! Cheers x

Do introductions slowly. Can you keep your group separate for a while? In a bathroom with food litter and toys? Take a towel and rub in on yours and leave it with the others; do the same with the others and leave it with yours.

Feed them on either side of the door so they associate good things with the new cats. After about a week, dab all cat necks with a drop of vanilla (between the shoulders). Let them mix for supervised visits.

Everything should be OK even if there is some hissing and posturing at first. I hope this helps.

yeah i can keep them seperate no problem. Thanks a lot for your help. What does the vanilla do?