Ibs

Hi,
Our local rescue has a beautiful cat looking to be rehomed, they say she has IBS and will probably need a special diet for life. Before I contact them and get too involved! I would like some advice, if any of you have experience with this.
Such as would it harm my other cats to feed them the same food as her? They are free fed James Welbeloved dry and sachets for breakfast and supper, and it would be difficult to feed another cat separately.

Thanks Anne