The director of our department often co-opts our ideas and has more investigators pursue them. The guy I share an office with was recently awarded a $1.8M grant for work that mk and I started. Honestly, it doesn't bother me that much, because we kind of have a communist system in out department. We all see some benefit, and the director knows what's what. That said, I would love a whopper of a grant like that for my own CV.
Isn't it considered part of teaching? It is not like I have 30 conferences a year and its just one of them. It would be my second conference ever. And I have the feeling that I can present my own work much better than my colleague, and answer the questions that might come up much better...
Communication is undervalued, perhaps you ought to communicate your feelings to the appropriate person in a constructive way.