If by later date you mean in a month or two yes, but if you mean a year from now, the answer is no.

With these batteries they go to a lot of trouble to keep all the cells identical.  They have cell balancing within the battery to keep all the cells at exactly the same state of charge as their neighbors, and then with multiple batteries they want you to make all the wires the same length so each battery does exactly the same amount of work as its neighbor.   When they go to all this trouble to keep every cell identical to all the others you can see why they don't really want you to come along and add a new battery a year from now, it would interfere with the balance of the system.