I have been in my current office role about 2.5 years. About 6 months ago, a new colleague started in a different team but same department. She is the same level of seniority as myself, but whilst her role has some overlaps in terms of specialty/expertise area with my role, it's a substantially different role in a different team, with a different line manager. She does however have a reputation- both externally and internally- as being extremely good and knowledgeable at this specialty/expertise area that is primarily the focus of my role (an area which only overlaps somewhat with her current role), and this is mainly due to her previous roles in which she did work in what is now my area.
She is also very proactive and enthusiastic and wants to help out in my specialty/expertise area and as mentioned would be very capable to do so due to the vast amount of knowledge and experience she has in this. I should add- I also have knowledge and experience in my area, but she has an external reputation I simply can't top (imagine hypothetically if your area was energy security and the new starter is the former energy security minister).
On a personal level, she is a great colleague to be around and work with. All good so far. The problem is that due to her willingness and exceptional reputation she is starting to get more direct invites to work in my specialty/expertise area and sometimes not along side me, but instead of me. This makes me feel excluded from my own role and like I'm being surreptitiously replaced. She has also been offering internal training in my specialty/expertise area, at first just to her own team, but the target audience for this has been gradually expanding.
So she is doing all this in an area that is not what her main role is about and I think it's because she is also so very competent in her actual role, that she does it really quickly and efficiently so has time (and interest) to take on more/something more challenging. Her line manager knows and approves.
Do you have any advice on how I could broach this at work either with her, my manager, her manager, others at work, without coming across as a jealous insecure mess? I'm trying very hard not to appear to be competing with her or bothered by her taking over my work. I just want to still be able to do my role without feeling that my knowledge and experience in my area is undermined. I don't want to lose 'clients' as it were because an increasing number of colleagues are recommending going to her for this area, instead of me, even though technically this is my area and not hers.