What to do when someone is stealing your cat's affection?

I adopted a cute little 11 week old bengal/tabby mix last week from an animal shelter because it broke my heart to see that baby in a cage. My boyfriend and I thought this would be the perfect chance to add to our relationship by having a little pet that we share so we agreed to get him and named him Floki. I am in college and live in a dorm a few days a week and cannot have a pet so we came to the decision that it would be best to keep Floki at his house when I'm staying in a dorm and when I go back home for the last part of the week then Floki would be with me. My boyfriend lives with his mother and step-father who also loves cats. Since Floki is staying at their house a few days a week, they have been acting like he is their cat. They have even been trying to change his name to something that they like and when my boyfriend informs them that he will be taking Floki to my house for a few days, they get upset as if he is taking their cat away. My boyfriend has to constantly remind them that Floki is not their cat and is my cat. I signed the adoption papers, I bought him toys and a scratching post and a bed, and I provide food and litter for him and take him to the vet. My boyfriend's parents don't pay for anything with Floki and I'm not asking them to. I am also afraid that since I'm not there and they refuse to acknowledge that he is my cat, that Floki will become more affectionate to them because they refuse to draw a line with their affection. I'm not asking for them to ignore him but I also don't appreciate it that they coddle him every second. I don't know what to do. Any advice would be appreciated.

I know it's not what you want to hear; but, honestly, there is very little you can do when Floki is in their house, even if you are paying for his supplies, etc...I'm also not sure I would suggest you ask them to refrain from interacting with him. He's a young kitten, so the amount of socialization he gets right now is pretty critical.

I understand that you want Floki to bond with you; but, only being able to have him with you a few days a week, there's a possibility he may bond with someone else, which includes your boyfriend's parents.

I think the only way for things to work out to your liking would be to have Floki living with you permanently. Is this a possibility in the near future? Where will you be living for the summer and when this coming fall? Will your school schedule be the same?

Starting next week I will be at home more often than not. My hopes are that he will bond with me more then. I understand he needs a lot of socialization, I just don't appreciate how my boyfriend's parents are going behind my back with trying to change his name and getting upset when I do have him for the latter half of the week.