Altering Sims' reactions to an object

This advice won't be very detailed because I'm just going off the top of my head here.
If you clone the bubble blower and go to the Warehouse tab in Studio, if you select any of the Object Definition entries, the panel on the right will tell you the name of the tuning that it is using near the bottom.
Now if you go to the Tools menu and select Extract Tuning... you can type in (or copy and paste) the tuning name. Click on the result and select to add it to your package.
Now that the tuning is in your package you can make changes and edit it. I haven't looked to see what code is in there though so I can't actually tell you what bits to change or edit here.
You can delete everything from your package other than the tuning part though as that is the only part you are actually replacing.