The current reading you saw in that forum post seems to be for a single type of servo. If you are using the same servo, those current rating might be okay, and you might be able to use the 9A regulator and a single battery.
If you are using a different servo the stall current is probably different than those measurements, so you should either measure the stall current or ask the manufacturer of your servos what the stall current is.
You can cut the + trace between the banks as shown in the picture with a hobby knife like an X-ACTO knife. Simply scoring across the trace until it is severed should work fine.