If he has designated her as his survivor.
No pension I know of allows a surviving child to inherit a portion of the pension. Is this some federal benefit I don't know about? If that is right, and a child can receive over half of the pension for his/her lifetime, then we REALLY need to take a look at federal employee benefits.
Can that be done with a non-spouse?
There are NO survivor benefits with a federal pension. There's a benefit for a spouse, or a former spouse with a court order, but you can't just tap into somebody's pension under either CSRS or FERS.