Multisite - process all transactions through one site


I can't find an answer to this question, was hoping that you might be able to help.

Basically, I am setting up a network of sites, all with specific 'products' for example, one site for recruitment, another for classified adds, another for property listings etc...

Is it possible that anyone who wants to advertise on the recruitment site can be directed to the main site for payment processing. Therefore allowing just one https:// at the tld and each sub-domain directing the tld for processing the order, thus keeping all of the transactions in one place?

In hope :wink: