Dear Friend,
As already stated, RUle 4 of CE Rules provides for such permission subject to certain conditions with respect to certain goods based on nature etc., Generally, this permission will be considered for seasonal products like Sugar et., and not for other goods.
I had an experience on the similar issue
Further, Rule 4 only says storage of goods in other place/premises and not clear whether other unit of the same manufacturer can also cover under this provision.
Instead, why don't you explore the possibility of single Registration in terms of the newly introduced provisions in the Budget since your units are situated in the same area this not only avoids multiple returns but also to address the storage problems.
Best Regards
Suryanarayana