How to get my SIL ring sized without being suspicious lol

Jalynn

Sooo, my supposed future brother in law text me a few minutes ago asking when I go to the mall with so and so (not saying names just in case lol) if I can get her sized for a ring without her knowing it was his idea.

Do you ladies have any ideas as to how I can go about this? I’m very excited about the task but I’m also nervous because I don’t want to screw it up. I was thinking of saying how I want to resize myself (I’ll be getting married in November) and if she wanted to check her size as well. So it wouldn’t seem too far fetched. Thank you all in advance!