One of the companies could buy the shareholding of the other for a nominal sum and would then take on the assets/liabities of the 'target' co.
In the long run it will lead to savings but in the short run you will need your solr./accountant to carry this out for you and they will be looking for a fee-it will involve extra filings with cro to advise cro of the situation.
But what you are proposing makes sense in the long run and you could still,if you wished maintain seperate bank accounts for both shops,which can be prudent if it is a high cash flow business(abc no. 1 a/c,abc no.2 a/c)
But talk to your accountant/solr first.