It has long been recognized that one or more of several persons jointly interested can bring an action in respect of joint property and if their right to sue is challenged can amend by joining their co-contractors as plaintiffs if they will consent or as co-defendants if they will not Such cases as Luke v. South Kensington Hotel Co. (1879) 11 Ch D 121 and Cullen v. Knowles (1898) 2 Q.B. 380 are