I have a new customer who has a walkway in the back lawn done with large flagstones over sand and it has (originally) blue star creeper planted between the stones. Now, the blue star creeper is inundated with spotted spurge, oxcalis clover and a few other weeds and they are mixed right in so if I spray the weeds I kill the plants. Ive cleaned it out but of course the spurge and clover came right back. I lifted one of the flagstones and its a mat of roots underneath now. Question is can the whole thing be killed and replanted with some chance that the weeds wont come back in? My feeling on it at this point is to pull up the stones, pour concrete and mortar the stones in.