A k-9 handler told me that dogs can smell weed or where weed touched for 2 weeks.
Roll a joint and grab a door handle, the handle will smell for 2 weeks. (To a dog)
Putting bud in a jar while wearing gloves. Being careful not to make any contact with the outside of the jar. Then after removing your gloves maintaining the no contact rule, with clean hands put the seal and outer ring on. Tighten securely. So far there has been no contact whatsoever. My last measure would be to melt wax in a saucepan and dip the top half of the jar to ensure a 100% seal. This would be a good way to package it so it didn't smell. I don't know how to package to send it via postal service. For over the road travel, wrapping the sealed jar like a birthday present is standard practice in my family.
I hope I was able to give you some ideas. I pray your sister may find relief from the chemo.
Californiakid