Follow-up: I called MM to ask about the status of my request. The agent told me she would send a request to Germany for an update and to call back the following week. I called back, as requested, yesterday, only to learn that MM insists that my segment EWR to SIN was "already credited" to another FFP. I reminded the agent that I had sent my original boarding passes to Verl, Germany, which had my MM account listed under my name, and that I only credit Star Alliance flights to my MM account. The agent agreed to ask which account the posting was made to and in whose name, as it clearly was not my account. As before, I was instructed to call back in one week.

And the adventure continues... Amazingly poor customer service on LH's part.