ive made Italian meringue buttercream befor and it was great, however this time i thought i would try white chocolate IMBC everything was fine untill i put the white chocolate in then it just went soupy so i put it in fridge and re whipped but it just will not thicken up any help would be great
thanks

The IMBC is a mixture of water end fat, wich normally wouldn't mix together, but under the right circumstances; temperature, amounts and beating it does. It only can handle a little twist or it will break again.
Maybe your chocolate was too warm, so it melted the IMBC, and after cooling the chocolate was too cold to get to the right consistency. Or it would have come together with longer beating. Maybe..

after having the white choc IMBC in fridge for 6 hours i piped 6 swirls onto a board to see if they would keep there shape overnight, yes they have kept there shape and taste fab just like a magnam ice cream still extreamly soft like soft whipped cream is this still SAFE to eat ?

It's fine to eat, just keep it refrigerated until you need to put it out or it sounds like it will soften up again.