variable advantage and existing advantages

[altamaros]

Can a advantage, in a variable advantage pool, be used to complete a existing external advantage ?

example :

Energy blast :XD6
+ 1/2 END +1/4
+ Variable advantage (+1/2): +1

can i use the variable avantage to complete the END advantage to 0 END (and then, use the remaining 1/4 to something else) ?

If yes:
How can i manage a possible increase of cost from other advantages ? :
Ex: if i want to use the above VA to put a "autofire" on my EB; the 1/2 END cost is supposed to increase to +1/2.

[Steve Long]

As a default rule, yes, but the GM is free to forbid this if he feels it would cause game balance problems.

Re: your second question, if you don't have enough Variable Advantages to absorb the increased value, you're just going to have to pay the extra END cost.