You will need to take the following steps in QBO if you need to enter a single transaction split between two vendors.
In this example, the transaction amount is $11.23 and you want to split between two vendors (vendor A = $6.23 and vendors B = $5.00).
#1 Enter manually those two vendors as a Bill (Create “+” sign > Vendors > Bill)
#2 Go back to the Banking Center (Left navigation bar > Transactions > Banking)
Click the transaction row for $11.23
Switch from “Add” to “Find Match” (See screenshot 1)
Select two transactions ($6.00 + $5.23) to match (See screenshot 2)