Really paranoid about house situation

So I've signed a contract to live with two others next year but one of these people has fallen out with me big time and refuses to speak to me, but has said they will be civil e.g they will reply to my messages. Trouble is I have this feeling that the person who I've fallen out with is going to try and find and replacement tenant for me, and i know they are good friends with someone who doesn't yet have a house sorted for next year.

If they do approach me and say that they want her to replace me in the contact, where do I stand?

Also what happens if I said no to this replacement tenant for myself and then as a result both the other 2 decide that they are going to find two replacement housemates. What would I do in this situation, would I have a right to object to the two people who are replacing me?

Thanks for the advice in advance

Without looking at the contract, if you've already signed you should be safe since you need to agree to be replaced, if they choose to move out they will probably have to carry on paying until they find a replacement.
Not sure though, ask the agent

Second what @TheGreatPumpkin said!

Is it possible to find another housing situation though? Having lived for a year in a similar situation, I can assure you it's worth the time and effort to try and find a different situation!

So I've signed a contract to live with two others next year but one of these people has fallen out with me big time and refuses to speak to me, but has said they will be civil e.g they will reply to my messages. Trouble is I have this feeling that the person who I've fallen out with is going to try and find and replacement tenant for me, and i know they are good friends with someone who doesn't yet have a house sorted for next year.

If they do approach me and say that they want her to replace me in the contact, where do I stand?

What does the tenancy agreement say about it? Ordinarily I don't think they can force you out, even if both of them want you out. You would have to agree to it.