Collections on the same Volume

[Carol C. Kankelborg]

Hi,
  I would like to know what the advantages and disadvantages are to having multiple DigiKam local collections? 

I am moving my parents’ photo collections (both are now deceased) into my world and would like to keep them separate as I sort through them. I would like to be able to work with just their photos (or mine) without seeing the others in search results or other filters along the left side bar such as Date, Faces. However, I would also like to work with both collections as needed, such as finding duplicates. Once I have sorted through their photos and decided which ones to keep, I will eventually merge them into my own collection.

What would be the best approach—keeping my photos and my parents’ in separate collections or in separate albums within one collection?  What are the pros and cons of each approach?

Thanks,
Carol