How to charge/balance two TrakPower's

I did get a reply from FP, they wrote:

You can use 2 Balancers in parallel to charge 2 packs at the same time
since you are using them together. This is not recommended however if
the packs are used separately.

So now my new question is...how exactly does one hook up two batteries each with their own V-Balance in "Parallel"...what does this mean?

Sorry for the low tech question but this is new territory for me.

Thanks,

DM