If, in an action (the principal action ), a claim is made by way of set-off, counterclaim or cross-action, the claim, for this Act—
(a) is a separate action; and
(b) is, as against a person against whom the claim is made, brought on the only or earlier of such of the following dates as are applicable:
(i) the date when he or she becomes a party to the principal action;
(ii) the date when he or she becomes a party to the claim.