InterUnit Entries in ePro

Hello all -

We are on version 9.1 bundle 11 -

We have 1 ePro share services business unit, but the a requested item  can be paid out of multiple GL business units.  When we have multiple GL business units on an ePro req, the GL group is saying that we are not producing interunit entries - and they have to create the entries manually

I looked at the system interunit transaction map and didn't see anything for purchasing so does this functionality not exist?  Is it something that must be handled manually or through a customization?

I've never had to deal with this scenario, so any guidance would be greatly appreciated