Back&#45;to&#45;back allowances anchor a 12&#45;race Saturday program at Gulfstream Park in south Florida, where both races are part of another burgeoning jackpot in the Rainbow 6.Races 10 and 11 are both for 3&#45;year&#45;olds and up and include claiming options in the race conditions. Neither has a standout favorite, although Tyler Gaffalione and Edgard Zayas, as usual, have calls on top contenders in both spots.Both co&#45;features are key links in a Rainbow 6 sequence that spans races 7&#45;12. The four&#45;day Gulfstream race week began Thursday with a rollover of $251,865 in the 20&#45;cent Rainbow 6, which requires a lone perfect ticket for a jackpot sweep.Race 10 is a $43,000, first&#45;level turf route. Gaffalione, the runaway leader at the Gulfstream spring meet (April 5 to June 30) and currently in a tight duel with Zayas for top honors at the summer meet, is named aboard Hammers Terror, an earner of $522,002 from 42 career starts. Reclaimed in April by trainer Mike Maker on behalf of owner Michael Hui following just one start for outside connections, Hammers Terror is one of four in this 10&#45;horse field entered for the optional $25,000 tag.Zayas counters with Durocher, already a three&#45;time winner over the Gulfstream turf this year, for trainer Harry Benson.Race 11 is a $44,000, second&#45;level, main&#45;track sprint in which Gaffalione and Zayas both have live mounts when starting alongside each other.Gaffalione will be astride French Quarter (post 5), one of four in this field of seven entered for the optional $62,500 tag. Trained by David Fawkes, French Quarter has been second or third in all five starts &ndash; including three ungraded stakes attempts &ndash; since being claimed in March for this same $62,500 price.Zayas has the speedy R Limo Joe (post 6) looking to up his record to 3 for 3 since being turned over to high&#45;percentage trainer Ralph Ziadie.Into Thursday, Zayas led Gaffalione in wins by a 18&#45;17 count at the summer meet, which began July 1 and ends Sept. 30.First post Saturday is 12:45 p.m. Eastern. The Rainbow 6 starts at 3:54, and the co&#45;features go at 5:30 and 6:04.Established Rainbow 6 patterns show that it&rsquo;s possible, albeit unlikely, that the jackpot would be emptied on either of the two Gulfstream programs prior to Saturday.The next stakes date at Gulfstream is Aug. 5, when the first two races in the annual Florida Sire Stakes series for 2&#45;year&#45;olds will be held.