German phrase
Möchten Sie am ~ teilnehmen?
Meaning
Would you like to participate in ___?
When to use it
It politely asks you to join. Use it in formal settings or with people you do not know well.
Example dialogue
Möchten Sie am nächsten Freitag teilnehmen?
Would you like to participate next Friday?
Ja, gern. Um wie viel Uhr beginnt es?
Yes, I would be happy to. What time does it start?