The following year in the tenth season, 1969 - 1970, Steve remarries, taking widowed teacher Barbara Harper (Beverly Garland) as his wife; she brings with her a 5 - year - old daughter, Dorothy "Dodie '' (Dawn Lyn), so Steven now had a stepdaughter whom he also subsequently adopts. (Dodie is wary of Steve at first, believing that he wants her to simply forget her late father, until he explains that he wants her to always remember and love him, but since he 's no longer alive, Steve wants to raise her in his place, and hopes she 'll come to love him also.) Also, the last year - and - a-half of the series feature fewer appearances of both Don Grady and Stanley Livingston. Grady 's character was written out of the show at the end of the 11th season, which allowed for his wife Katie and their triplet sons to remain within the Douglas household the following season (as a structural engineer Robbie was working on a bridge construction in Peru). Chip and his teenaged wife Polly (Ronne Troup) (who eloped after Polly 's disciplinarian father refused to sanction their marriage) move into their own apartment.
who does chip marry on my three sons
Polly Polly