If it is your spouse, you can get an HHonors Mutual fund (marketing speak for joint account). Then with many airlines you can convert miles from your separate FF accounts into the same HH points account.

It isn't economical to use Hilton to launder miles to points to miles because you lose so much. But you can do some research on the HH website to see if you might get a useful air reward direct from HH by using points instead of miles, especially after you combine.

www.hhonors.com