MLT DESCENDED INTO CONFLICT WITH ACR MLG RESULTING IN LESS THAN STANDARD SEPARATION.

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I WAS THE RADAR CTLR AT THE MYS HI SECTOR ALT LIMITS FL350 AND ABOVE. ON MY FREQ WAS MLT X AT FL390 ADW TO BLV. MLT X REQUESTED FL180 DUE TO STRONG HEADWINDS AT THE HIGHER ALTS. THE WINDS WERE 275 DEGS; 130+ KTS. I CLRD MLT X TO DES TO FL370 TO REMAIN CLR OF 2 ACFT NBOUND AT FL350. AT THIS TIME I ENTERED FL180 INTO THE COMPUTER AS ASSIGNED ALT AND FL370 AS TEMPORARY ALT. ALSO; I PUT A DODECAGON ON THE RADAR TARGET OF MLT X. PRIOR TO MLT X BEING CLR OF THE NBOUND TFC; I PUT TEMPORARY ALT OF FL240 IN THE DATA BLOCK OF MLT X AND HANDED MLT X OFF TO PXV HI SECTOR. THE HANDOFF WAS IMMEDIATELY ACCEPTED BY PXV HI. WHEN MLT X WAS CLR OF MY NBOUND TFC I DESCENDED MLT X TO FL240 AND SWITCHED MLT X TO PXV HI FREQ. WHEN PXV HI ACCEPTED THE HANDOFF ON MLT X THEY PLACED AN ELECTRONIC PVD ON MY SSH ON MLG Y SWBND AT FL350. NO VERBAL POINTOUT; APPROVAL OR COORD WAS MADE BY PXV HI. MLG Y ENTERED MY SSH AIRSPACE. AFTER LISTENING TO THE TAPES AND REVIEWING THE MULTITUDES OF CHARTS AND GRAPHS THAT OUR QUALITY ASSURANCE DEPT COMES UP WITH; I FEEL SEP COULD HAVE BEEN MAINTAINED HAD THE PXV HI CTLR TAKEN ACTION SOONER AND TAKEN APPROPRIATE ACTION. NO ACTION WAS TAKEN FOR SOME TIME (1-2 MINS) AFTER MLT X CHKED ON FREQ. WHEN ACTION WAS TAKEN TO SEP MLT X FROM MLG Y THE PXV HI CTLR CLRD; 'WRONG ACR MLT;' TO TURN TO A HDG. THERE WAS NO RESPONSE AS THE CTLR MEANT TO TURN MLG Y. HOWEVER; IN RETROSPECT; HAD I NOT DESCENDED MLT X THIS WOULD NEVER HAVE HAPPENED. HINDSIGHT IS ALWAYS 20/20. SUPPLEMENTAL INFORMATION FROM ACN 80494: AT THE TIME I REALIZED MLT X MIGHT BE IN CONFLICTION WITH MLG Y BUT THOUGHT TO MYSELF THERE WAS PLENTY OF TIME TO GET MLT X UNDER MLG Y. (I DIDN'T REALIZE MYSTIC HAD NBOUND TFC HE WAS WAITING TO CLR). SO; I CONTINUED TO SEARCH FOR ACR FLT Z. JUST AS I FOUND THE LOCATION OF THIS FLT MLT X CALLED ON MY FREQ OUT OF FL368 FOR FL240. I SWITCHED ACR FLT Z TO THE CORRECT FREQ AND ISSUED A 30 DEG LEFT TURN TO BOTH ACFT AND TOLD MLT X TO EXPEDITE THROUGH FL330. SEP WAS LOST WITH 3.5 MI AND THE SAME ALT.