Topeka is simulcast I think at some point, not sure they will listen to them much. Their closest tower/repeater I think is. Does that make sense?
You comment was that your folks "live outside of Topeka". The key is how far, and in what direction. There are a number of systems here in my area (DFW Metro) that have simulcast issues for scanner owners. However, I am not affected by them as I live outside their primary coverage area. Close enough to hear them, but far enough away that I don't get hammered with simulcast distortion. That likely will change late next year when Dallas (city) and Dallas County move from their Uhf Conventional (city) & Vhf-high (county) systems to a new P25 Phase II simulcast system that is currently being built. That's why I purchaed the SDS series scanners; not currently needed, but in preparation for the changeover.
The map of the simulcast locations for the Shawnee County system that Topeka is on is here:
https://www.radioreference.com/apps/db/?action=siteFCCMap&siteId=22067
Here's the image:
Depending on your parents location relative to the tower sites, they may, or may not, have any issues. If you know someone with a digital scanner, other than the SDS100 that you have, you might ask to borrow it long enough to verify whether or not there was a simulcast issue at your parents location. If they are very close to
one of the tower sites, that signal strength might override any distortion. But if they were near where 'Silver Lake' is labeled on the map, they'd be between several sites, of varying distances, which can be a problem. Your best bet, if possible, is to try a similar scanner (not the SDS series, which was intended to deal with simulcast) and see how it performs. Your other unknown (not mentioned in your first post) is whether they intend to use the HP-2 as a table top scanner, with an attached antenna, or if an external antenna of some kind would be used.
Since the Shawnee system, as well as the statewide KSICS system are both Phase I, you would not need to try a Phase 2 capable scanner at their location. I presume, if either system was projected to upgrade to Phase II, that this would be discussed down in the Kansas Regional forum.