Upvote:3
If both flights are on the same ticket (single booking), than this should be no problem. Bangkok Airways has an interline agreement with Lufthansa from USM. Minimum connection time in BKK is 75 minutes.
See http://www.bangkokair.com/pages/view/check-in-through
If it's on two separate tickets, than all bets are off and this is unlikely to work.