Your limited to 8 accounts/games on the one B.Net.
But whether they're on the same B.Net or different ones, you can RAF freely either way.

From an RAF point of view, its a referring account and an account which was referred.
Your chain is going to be the same.

If you're adding five accounts, I'd really suggest going with a chain like this:
X > A > B > C
A > D > E

X will be an existing account, whose only purpose in this chain is to refer A... so they can receive granted levels and a free month; they will have absolutely nothing to do with the boosting/grouping of the A/B/C/D/E accounts.
A is one of the new accounts, on the existing B.Net account that at least one of the five previous accounts was on.
Because A (new account) is on the same B.Net as the existing account(s), you can toon transfer very quickly.
So transfer a strong booster to A (new), from an existing account.

And then boost the piss out of the others...
Essentially treat the new five accounts as brand new, on a new server with a booster that transferred there.

The double chain (A > B > C ... and A > D > E) results in a lot of granted levels to A...
Which will need new toons, because aside from the booster it is an empty account.

Naturally, you can use the resources of your first five accounts...
For bags or whatever else you'd like.
You could auto-follow the others, and heal as needed.
Or just be there to blow shit up, particularly on a PvP server if ganking is an issue.

Once you have several toons on the new five accounts.
Decide how you want to integrate the new five with the existing five.