Hello everyone, and apologies in advance if it's a silly question but I couldn't find an answer in this forum.

I have an UA ticket FCO-IAD-ASE/ASE-DEN-FRA-FCO. The return leg (DEN-FRA-FCO) is operated by LH, of which I am FTL with over 200,000 miles.

I called LH to upgrade the DEN-FRA but they tell me the booking class (L) is too low so I should call UA to see if it's possible to upgrade to V and then the upgrade would be possibile.

I called UA in Italy and they say a) I can't upgrade with miles because I am an LH FTL and b) I should contact my travel agent in the US to make a pay upgrade to V.

So I was wondering: is it possible in your knowledge to transfer miles from LH to Mileage plus, and then using the miles to upgrade?

A bit complicated, I know... thanks for any assistance/wisdom you are willing to share. I would like to avoid coming back in row 47

Thanks

Carlo