Hello and thank you for your question.
From what I can tell you are selling the products that you are holding on a consignment basis for others.
When you collect the money from the sales, you would (total debits = total credits):
Credit commission income for the fees you get to keep
Credit sales tax liability for the sales tax due
Credit a liability account for the amount due to the actual seller
When you pay the sales tax:
Debit sales tax liability
When you pay the actual seller their proceeds, less your fees:
Debit liability to actual seller
Notice how there was really no expense to record in all of that.
I hope this was helpful.