Allow users to replace image on protected sheet , but lock image size

[J00490]

I have a locked sheet where I want a user to be able to replace a 'generic image' with a photo they've taken, but the photo has to resize to fit the shape of the original 'generic image' otherwise it overlaps other data and resizing it each time is a chore (there could be up to 20 instances of this on the sheet).

Currently I am looking at the VBA code suggested here (Allow user to change instered picture on protected sheet) to allow replacing the 'generic image' but I can't figure out how to lock the size of the new picture as I am no good with VBA.