Help needed! (Use of FC miles on partner flights)

Hi all,
I've been racking my brains on how best to help my sister out with my FC miles - she's going travelling this summer leaving in mid-July and coming back mid-Sept. Route to include London (LHR) - Monterrey (MTY) - Lima (LIM) - London (LHR).
So far, I've found the best route to probably be with Continental via Houston (full price 1,135), and I was planning to buy my sister the LHR-IAH-LHR sectors, at a cost of 50,000 miles. However, after phoning Virgin FC, they said there was no availability on Continental throughout June, July or August for reward seats.
So, does anyone have any thoughts on:
(1) How easy it is to get reward seats on Continental (with FC miles); and
(2) Whether there's another route I could consider to help my sister out.
Thanks tons in advance for your help
I've been racking my brains on how best to help my sister out with my FC miles - she's going travelling this summer leaving in mid-July and coming back mid-Sept. Route to include London (LHR) - Monterrey (MTY) - Lima (LIM) - London (LHR).
So far, I've found the best route to probably be with Continental via Houston (full price 1,135), and I was planning to buy my sister the LHR-IAH-LHR sectors, at a cost of 50,000 miles. However, after phoning Virgin FC, they said there was no availability on Continental throughout June, July or August for reward seats.
So, does anyone have any thoughts on:
(1) How easy it is to get reward seats on Continental (with FC miles); and
(2) Whether there's another route I could consider to help my sister out.
Thanks tons in advance for your help
