I need to boss on to an old push fit branch, however the poly pipe boss adaptors I carry are way too big. The internal diameter of the boss is around 49-50mm. Tried 50mm pipe in the boss and it doesn’t fit, a 50mm fitting doesn’t fit over the outside of it either. Any ideas what I need? Think it may be made by Marley? It looks like all the Marley boss adaptors I can find online go straight to push fit, ideally I want to use solvent weld. Also what suppliers stock Marley fittings?