In a word, Yes.
The repair can be affected in a few different ways but the tear is symptomatic of the overall condition of the leather and the 'repair' would be cosmetic, at best, lasting a short time. The boot would not be serviceable in the usual practical sense.
Edit: Here's one idea; however, it will affect the fit. The 'stent' will also help reinforce the surrounding upper. GoreTex™ may be suitable. There are a variety of different glues/cements - consult technical references for the appropriate one.
… Preserve them as a cherished memento of your loved one. A specialty frame shop professional would be able to give you some ideas for display if you were so motivated.