Moving from VPP to Apple School Manager

Currently, we use ASM with Meraki as our MDM. We have been purchasing apps through our VPP account (which is linked to Meraki). The VPP no longer allows us to make purchases and says we must migrate to ASM.

We've added a second MDM (Lightspeed) to ASM and will want to purchase apps for the devices it will manage as well as for the existing devices managed by Meraki

How do we migrate the VPP to ASM and ensure that existing purchased licences stay with the Meriki MDM as well a allowing new purchases to be made for both MDMs?

Thanks

Barley