I don't think so. you need a way of connecting the back boiler into a
circuit that can safely dissipate its heat, maybe something on the
return side to the oil boiler but I'm no plumber.

A Dunsley neutraliser would work, although this might not be compatible with
the oil boiler, if it requires sealed pressurised operation. It would have
the additional advantage of actually using the solid fuel to heat the water.

An alternative, although probably too late to consider now, is to use a heat
bank in these situations. The oil/gas sealed pressurised boiler heats the
tank up through the indirect coil in the normal way. The solid fuel range
heats through direct water circulation with the heat bank water (no valves
or restrictions required) and the DHW is mains water heated off the plate
exchanger. A byproduct of this design is to provide mains pressure hot
drinking water.

Christian.