Parent term checkbox should not automatically be checked when child term is checked

I have a hierarchical taxonomy I'm using as a facet that loads up looking something like (expanded by default):

[ ] Family (6)
    [ ] Adoption (2)
    [ ] Child Support (5)

If I select Adoption, I correctly receive a list of 2 items, and have an URL like:

/search_page/keyword?f[0]=im_field_topics%3A97

However, when the results load, both the Family and Adoption checkboxes are checked (though their counts go away), like:

[x] Family
    [x] Adoption
    [ ] Child Support (5)

This seems fine at first, but now the user has no way to add the 6 items tagged with the parent term (Family). Further, if I start over and first select Family, I get (as expected) 6 results and the UI shows:

[x] Family
    [ ] Adoption (2)
    [ ] Child Support (5)

However, if I then click Adoption, I receive a total of 8 results (those for both parent and child) with a URL like:

/search_page/keyword?f[0]=im_field_topics%3A102&f[1]=im_field_topics%3A97

...but the UI looks the same as in the first example when I was only filtering on the child term:

[x] Family
    [x] Adoption
    [ ] Child Support (5)

So... same UI representation for two different results.

I took a look at the Javascript code doing the checkboxes, but it seems like the issue may go all the way back to when it's being decided whether or not a given term is "active". I suppose we may need to distinguish between "active" and "active_trail" or somesuch. Thoughts?

Thanks for all the great work!