After 3 months, just got a resign letter from her, 1 month notice. So, if your 姐姐 need you to write something like reference letter to prove you have been employed her since xxx, then you better prepare to find a new 姐姐.
College Education. Not u grad.
No remember which subject she study, something like care taking / nursing....
As so many people here say don't write / sign the reference letter,
I actually haven't just the reference letter for her.
Anyway, just don't sign anything is better.
But you say. (佢地可以造假,真係防不勝防喎!)
From info/cases in BK here, if she gets a offer from canada, she will normally just give a short notice to u (i.e 7 days)