ACR Y CLB THROUGH OCCUPIED ALT HAD LTSS FROM ACR X. SYS ERROR.

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I HAD ACR X DH7 DEPART PHL SWBOUND CLBING TO 5000 FT. ABOUT 7500 FT W OF PHL; I HAD TURNED THE DH7 WBOUND TOWARDS HIS FIRST FIX AND CLBED HIM TO HIS FINAL ALT OF 8000 FT. HE REQUESTED A DEV AROUND WX IN THE S OF HIM AND WANTED A TURN TO THE NW. I APPROVED IT AND HAD TO GET A POINTOUT FROM AN ADJACENT CTLR BECAUSE HE WOULD FLY INTO HIS AIRSPACE. I THEN GAVE A RELIEF BRIEFING TO ANOTHER CTLR. IN THE MIDDLE OF THE BRIEFING ACR Y; B75 DEPARTED PHL SW OFF RWY 27 ON A 255 DEG HDG. I DID NOT RESPOND TO HIM INITIALLY BECAUSE I WAS STILL GIVING THE BRIEFING. I ALMOST FINISHED THE BRIEF WHEN THE RELIEVING CTLR WAS TOLD TO UNPLUG AND ANOTHER CTLR WAS TOLD TO RELIEVE ME. I THEN RESPONDED TO THE B735 TO CLB TO 10000 FT (OUR HIGHEST DEP ALT). I THEN STARTED GIVING THE 2ND BRIEFING AND MIDWAY THROUGH THE BRIEFING; THE B735 SAID HE WOULD LIKE TO TURN E (HIS DIRECTION OF FLT). I THEN RECOGNIZED THAT THE B735 WAS ABOUT 1 1/2 MI BEHIND THE DH7 AND ABOUT 500 FT APART. I STOPPED THE B735 ALT AT 7000 FT; TURNED HIM EBOUND; AND ISSUED TFC. I BELIEVE THAT THE DEV AROUND WX AND ISSUING 2 RELIEF BRIEFING CONTRIBUTED TO THE SIT.