Partial enhancements

[CeeDub]

Hello, I'm new here. Hopefully not just passing through, though.

Apologies if this has been covered before, but I couldn't find anything pertinent with the search terms I could come up with.

I was wondering if it is possible to buy certain enhancements only for some of the levels of the modified advantage, and if so, how.

Example: I'm trying to build a TK (or PK, if you prefer) with say 15 levels in TK. I want her to also have the ability to manipulate a larger number of items in an area than what would be possible with the "two invisible hands" approach. To reflect that she is spreading her TK strength thinly over an area instead of a focused application and/or to reflect that this is an application of her talent she is still developing, she only has a more limited ST with Area Effect.

Could I buy e.g. 5 levels of Telekinesis (5/level, Area Effect +50%, Selectivity +10%, Psionic -10%) [38] and +10 levels of regular Telekinesis (Psionic -10%) [45]? Do I need to buy 15 levels and 5 levels separately? Something else I should have thought of?