Legal Question in Real Estate Law in New Hampshire

Probably not. A deed is evidence of ownership of rela estate and his girlfriend has the deed.

Start by reviewing the chain of title. Generally, the deed transfers all ownership to the girlfriend. However, it is possible he retained some rights either as a co-owner or by life estate. Next, is there any documentation between your father and his girlfriend? Is there any agreement as to payment of monies for the property? Lastly, was there a will and was the property specifically referenced in the will?

Unfortunately, greater detail is needed to determine if you and your sibiling have any rights or claim.