Rejecting an offer for MS and applying to the same school for PhD

[anya11]

I have an offer for MS from this school X. It is in the top ten schools but not higher than school Y. I intend on applying for Phd after MS in a closely related field but not in the same discipline. School Y is better for MS but X is the best for Phd and a good fit based on my interest.

Considering fin aid is not a prob for masters should i choose Y over X for MS and come back to X for Phd? 

Will rejecting the offer from X affect my chances for admission to Phd thr? 

[origin415]

I don't know how taking the MS elsewhere will affect your chances (I would guess not a lot), but I don't think that where you got your MS will matter much if you have a PhD, so the fact that you went to Y for your MS then X for your PhD will not look better than going to X for both.