Jammu and Kashmir has a good shot. OTL, the Maharaja invited Indian forces in to help fight Pakistani forces that had invaded on the invitation of local Muslim rebels, and the end result was a ceasefire and de facto partition. A potential easy solution would be to make it so that the leader of the rebellion is captured or killed by the Maharaja's forces instead of making it to Lahore and convincing the Pakistani government to support him. Aside from that, I don't know how strong the support was within Lahore to back him; it might be easy enough to disrupt in any way.
An interesting idea might be to try and get UN involvement. This is before the OTL earliest UN peacekeeping (which was in 1948 following the Partition of Palestine), but it could set an interesting precedent.