ABC, looking to give spring tryouts to a number of backup and benched series, has announced lineup changes for March affecting five nights of programming.The moves include placing the new comedies “Getting By” and “Where I Live” from 9-10 p.m. on Fridays beginning March 5, introducing the in-house drama “Sirens” at 10 p.m. Wednesdays starting March 10 and returning the on-hiatus drama “Homefront” to its original Tuesday 10 p.m. slot beginning March 9. In addition, “America’s Funniest Home Videos” and the Friday sitcom “Dinosaurs” will slide up to fill the 7 p.m. hour Sundays starting March 7, to be followed by ABC’s new Forrest Sawyer-hosted prime time news hour. Current Sunday hour “Life Goes On” will complete its run with two Saturday night airings, March 20 and 27, serving as the lead-in to “The Young Indiana Jones Chronicles,” which returns with a two-hour installment March 13 and then will air regularly at 9 p.m. Saturdays. Nothing has been set to occupy the lead-off hour Saturday beyond that point. Three shows disappear in the shuffling: in-house sitcom “Camp Wilder” closes its tent Feb. 26, the Steven Bochco series “Civil Wars” tries its last case for the 1992-93 term March 2, and “America’s Funniest People” goes on hiatus until May, when it will return with new episodes. Another first-year hour, “Going to Extremes,” had been airing Wednesdays and was already yanked. The scheduling changes, which touch every night but Monday and Thursday, would seem to risk confusing viewers about where to find shows–something ABC pledged not to do before the season. A spokesman noted that the web needed to give its midseason product a shot. NBC is in the process of enacting its own shifts, and CBS also has several series to get on the air before schedules for 1993-94 are set in May. With the Saturday time period, ABC is seen as simply burning off its expensive commitment to Paramount and George Lucas on “Young Indy,” which flopped earlier this year in a Monday slot. Other ABC shows yet to return include the Universal sitcom “Home Free” and the on-hiatus comedy “Delta.” With the changes, ABC will be supplying itself six series accounting for more than a quarter of its 22-hour weekly prime time sked.