Yes you can do overlays with Brisa Lite Removable Sculpting gel, but why would she prefer that rather than a gel polish? That really doesn't make any sense unless she is worried about her nails being buffed.
The smoothing gel plus colour would be a far better and easier option for the client and a faster removal time. You may not have it in but I'd sure get some in because it is a winner for challenged nail clients.
We as technicians should be deciding the right options for clients, not the clients. I can't see her objection to gel polish other than the buffing of the nail plate before application ... But with CND you don't have to do that so I wonder why she feels she doesn't want the obvious option which would be Shellac?