[Cantab]

I have a (potential) new staff member that I want to sponsor for full time employment.
The problem is, she is already in the middle of a sponsorship process with another company (who are ripping her off).
What are the issues involved with my wanting to sponsor her now? Would she need to inform immigration or just cancel it through her current sponsor?
I'd assume that immigration would possibly look at this in a negative manner and I have no wish to get another company (or this girl) into trouble by telling IMM. that she is getting ripped off.
Advice?