Single buggy for autistic child aged 6 (lively) (Liskeard PL14)

I have twin autistic grandaughters , one of which is non verbal . The other you would not know . The NV girl needs to be in a buggy to go around places , she will run off and if only one adult is in charge then it causes great difficulty . So although she can walk perfectly well , and is sweetness and light most of the time , when things dont go her way she is more than I can handle .