What is the effect of making appellant a third party?

In my opinion the learned Chamber Judge was right in dismissing the appeal, and allowing the order, making appellant a third party, to stand. While appellant’s counsel fears that appellant may be prejudiced by being made a third party, he does not object to the specific directions given by the order appealed from, but, if he so desires, the following words, namely and in any event shall be at liberty to oppose the plaintiff’s claim so far as it might be affected thereby, and for this purpose might put in oral and documentary evidence, and cross-examine the plaintiffs’ witnesses, may be added after the words “the Judge shall direct” in the third paragraph of said order (Eden v. Weardale Iron & Coal Co., 34 Ch. D. 223, 56 L.J. Ch. 178).