What is the effect of the Agreement, Amendment, and Undertaking in relation to the construction of a dwelling house?

I should say at the outset that the consideration here involves agency principles and not the doctrine of merger. The deed delivered on closing was executed by the owner of the land who was a stranger to the construction undertakings and did not commit the grantor to perform anything relating to the dwelling house. It has all but been conceded, and it is evident from the record, that the collateral undertakings in the Agreement, the Amendment, and the Undertaking were intended by the parties to survive the closing: see Fraser-Reid v. Droumtsekas, 1979 CanLII 55 (SCC), [1980] 1 S.C.R. 720. What is at issue here is not the continuing existence of the undertakings, but upon whom the obligation to perform the undertakings now rests.