if there is a situation where there are 3 parties that own property that are within very close proximity of each other (e.g terraced housing), and party one had suffered damages to lets say tv antenna. Then party one and two (without the knowledge of party 3) come to an agreement to connect all 3 terraced houses into using 1 antenna instead of 3 different ones. party 2 then writes a written agreement. party 2 later lets party 3 know in which party 3 agrees and sends a message to party 1 saying that they would be accepting of the new changes. but once everything is installed and ready to go. party 2 and 3 starts having problems with the antenna and requests the assistance of party 1 (who set up and hired antenna installations). but party one lets both other parties know that they are no obliged to the other houses.

would this be a formalities, privity or formations question?