If you can, then buy the tickets separately and use miles to pre-confirm the LH segment. Use the SWUs transatlantic. I am sure that you would have to blow 4 SWUs on this trip anyway to upgrade the entire trip.

FRA to Alma Ata is not going to be fun in LH coach unless it's empty. I had a nice flight FRA-CAI but I was very lucky -- noone in front or next to me.

But I am guessing that the US govt insists that you buy the codeshare.