account Questions? (Top urgent)

My Co. set up a new Co.(B) to share the turnover of old Co, my boss ask me how to share the overheads of the old Co (A)

1) "A" Co sales some goods to B ,B sell to outsiders
2) basically, no overheads will occur in new Co, all work will be done by "A". for tax purpose, we need to share some overheads with A.
3) Management fee
is one of my idea,but any concen in IRD (I know some constriction
in mgmt Fee item
Any idea or suggestion for share of overhead?