This is a toughie. Apply Preen, or similar pre-emergent product. Put plastic bags over the flowers. Spray with Roundup. Pull the bags off. Wait about a week. Clean up the remainder with 1 ounce Roundup in a squirt bottle...protecting the flowers with a piece of plastic or a snow shovel in your left hand. Don't worry if you knock out a few flowers--explain to her in advance.
If you have not blown her budget yet...
You might try the kitchen tongs method. Attach absorbent cloth pads on both sides of ice tongs. Using Roundup solution, using a squirt bottle, spray the pads with solution until moist. Grab the weed near the base and pull the pads over the entire stem. Try to avoid hand weeding, but charge your regular rate if you need to...perhaps a dollar a minute...more, if its hot where you live. Some of these weeds will be killed by frost--by about Thanksgiving; use pre-emergent next year.