The partners in a new judicial marriage met each other informally for the first time yesterday when the 12 judges of a new nationwide appellate court, a consolidation of two old courts, held their first meeting together.

The new court, the Court of Appeals for the Federal Circuit, consolidates the U.S. Court of Claims and the U.S. Court of Customs and Patent Appeals, two relatively unknown but extremely powerful parts of the federal judiciary. The members don't have to function as one until October, under a law signed April 2 by President Reagan.

But they got together in advance to reach agreement on what one of the judges called "housekeeping" matters, such as whether the lawyers belonging to the separate bars of the old courts will be automatically admitted to the new combined bar. The judges decided they will, which, since there are 10,000 members, will save a lot of paper work.

The complicated area of patent law was the primary target of the consolidation. Under the old system, appeals from U.S. District Court decisions concerning, for example, the validity of a patent, could be heard at any U.S. Circuit Court of Appeals or at the patent court in Washington. The result, backers of consolidation contended, were rulings that often conflicted.