Michael J. Fox will have a fiancee when he returns to “Spin City” this fall: Former “Wonder Years” star Olivia d’Abo.D’Abo has signed on to appear in two of the three episodes Fox is slated to be in at the start of the season. DreamWorks Television announced Fox’s guest stint earlier this summer. Meanwhile, “Spin” producers say Farrah Fawcett has also agreed to appear in a couple of episodes sometime during the season. “Spin” will air Tuesdays at 9:30 p.m. this fall on ABC.