I was Alt at Valencia, not needed. Am I able to commit here?
Sorry, you can't
This is from the TT FAQ thread:
Can an alternate player of a certain tournament who didn't make the draw play in another tournament in the same week that has spots available?
No, players are only allowed to play one tournament per week. If the player sent picks as an alternate, they aren't allowed to play anywhere else that week even if they didn't make it to the draw.