Create a new formula:

if instr({CnPrProp_1_Solicitors}, ";")=0 then {CnPrProp_1_Solicitors}
else split(CnPrProp_1_Solicitors, "; ")[2]

This formula will split the proposal solicitors field on the semi-colon and place each name into an array. Then, the name in position 2 will be displayed.