Invoice different companies within same group

Is there a way to invoice different companies in the same group without creating separate customer entries for each?

No

The only way I have worked out with a work around is by setting up divisions for each sub company. and using the one the invoices

That won’t provide for separate invoicing.

You are right Tut sorry, It worked for everything else I have done but not invoices, thought it might of been an easy fix but I was wrong.