Under the rules of California and a number of other jurisdictions only aggreived parties can appeal a particular order or judgement.
The Calif. Supreme Court has defined an aggrieved party as one whose rights or interests are injuriously affected by a judgment. The party's interest 'must be immediate, pecuniary, and substantial and not nominal or a remote consequence of the judgment. . . . . ' Hensley v. Hensley (1987) 190 Cal.App.3d 895, 898-899.
See Rebney v. Wells Fargo Bank (1990) 220 Cal.App.3d 1117, 1132 [In determining whether party is aggrieved to have standing on appeal, '[t]he guiding principle is one often encountered in daily life: no harm, no foul.'].