ZID CTLR OBSERVED 4 SIMULTANEOUS TCASII RA'S WHEN FLT CREW FAILED TO ADHERE TO ASSIGNED XING RESTR WHILE FOURTH ACFT DSNDED ON A STACK OF 3 LOWER ACFT CAUSING RA WITH TOP ACFT.

Narrative

A320 WAS ISSUED XING AT FL340 AND WAS TRAVELING NBOUND. PLT ACKNOWLEDGED CLRNC. SECTOR TO THE N OF FALMOUTH COORD THAT HE HAD TFC AT FL340 AND REQUESTED THE A320 AT FL360 OR FL330. I REISSUED A XING TO A320 TO CROSS FLM AT FL330. PLT ACKNOWLEDGED CLRNC TO FL330 AT FLM. THEN I GOT NEW TFC FOR A320. A320 NBOUND HAD TFC CONVERGING AT FLM VOR (A D39-3) SEBOUND AT FL350 AND A H/B744 SWBOUND AT FL340. AS A320 GOT CLOSE TO FLM; I OBSERVED THAT HE WAS PROBABLY NOT GOING TO MAKE HIS XING; SO I ASKED THE PLT TO VERIFY HE WOULD MAKE THE XING. PLT ACKNOWLEDGED HE WOULD MAKE XING. AFTER THIS STATEMENT BY PLT; I INFORMED HIM THAT HE HAD TFC N OF HIM AT FL350 AND FL340. PLT ARRIVED OVER FLM AT FL360 AND DSNDED; WHICH CAUSED AN RA FOR DC93 AT FL350. THE A320 ANSWERED NEXT WITH AN RA. DC93 DSNDED TO RA AND A320 CLBED TO RA. THE DC93'S DSCNT CAUSED AN RA WITH AN H/B744 AT FL340. BEFORE THE RA EVENT WITH THE H/B744; I VECTORED HIM (H/B744) WHEN I WAS AWARE THAT THE A320 WAS NOT GOING TO MAKE HIS XING. I DID THIS FOR SAFETY; SO TARGETS WOULD NOT MERGE.