A call to Delta would give you the info you need. One of the pros here probably knows about what trim may be available. But, if the valve does not have anti-scald technology, and you're doing a remodel, code generally requires you to update the valve to one that has this, which may be a push for your wife. It would protect her, you, maybe the children from potentially getting scalded if there's a hiccup in the pressure by somebody flushing a toilet, etc. while you're in the shower.
Failing that, you can change the valve from the front if you make a bigger hole, then using a remodeling/rennovation plate. Delta, and others, make them in various finishes. The plate covers the bigger hole, and the new valve trim fits on it.