Insert lead into SFDC - going into wrong partition

I am trying to insert persons into SFDC via Marketo but:

1. They don't need to go into a campaign, just be assigned to a queue
2. It seems easy to just upload and add the flow step "sync to SFDC"
3. But we have 2 partitions in SFDC
4. If I use the flow step to add the leads, they are going to the wrong partition

Any tips on how to add them to SFDC as lead in the right partition?