term:

Join

join vt

1 : to unite so as to form one unit [ the claims in one action]
2 a : to align oneself with esp. in a legal matter [she ed her husband as plaintiff]
b : to cause or order (a person) to become a party to a lawsuit [if the person has not been so ed, the court shall order that the person be made a party "Federal Rules of Civil Procedure Rule 19(a)"] compare consolidate, implead, interplead, intervene
c : to enter into or participate in [ the suit]
vi
1 : to come together so as to form a unit [the other victims of the scheme ed in the suit]
2 : to commence involvement or participation [if the person should as a plaintiff but refuses to do so, the person may be made a defendant, or…an involuntary plaintiff "Federal Rules of Civil Procedure Rule 19(a)"]
join·able adj


join issue

or
join the issue

1 : to accept, fix on, or clearly define an issue as the subject of a legal dispute [refused to join issue by filing an answer with the court]
2 : to take an opposed position on some question [join issue with the conclusion]

Source: Merriam-Webster's Dictionary of Law ©1996. Merriam-Webster, Incorporated. Published under license with Merriam-Webster, Incorporated.