Question
What kind of product can be utilized to kill weeds that are coming up through established ground cover without killing the ground cover?

Answer
Hi Sherri,
Thanx for your question.  My fellow gardeners and I have often discussed this issue.  You can always spot treat weeds in and established area.  I use Roundup in a little bowl with a paint brush and carefully "paint" the offending weed.  If it's small and/or new, one treatment will usually do it.  You may have a small barespot for a while but the ground cover will usually fill in pretty fast.  I hope this helps.
Tom