That Common Travel Area Question again and visa stamp requirements

I have a Canadian friend who is flying from Canada to ROI, then onto the UK for a few days to see me, and then back to ROI for 24 - 48 hours before going back to Canada. She may spend time in NI before / after seeing me.

What, if anything, does she need to arrange to ensure she gets stamped in to the UK, if needed - don't think this happens between NI and ROI, but maybe something needs to be arranged between Dublin and Leeds?   

TIA! 

She won't be stamped traveling from Dublin to Leeds (the UK actually understand the Common Travel Area), but she'll get stamped coming back into Dublin (because they don't seem to understand it). She'll go through the non-EU line just like people flying from all over the world (or even other parts of Ireland). She shouldn't need anything as long as she has her itinerary and when asked how long she'll be in Ireland she can give them an answer. Tell her not to worry!

Excellent! Just as I thought. Thank you, B2UK.