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

Narrative

ACR X EBOUND OF ORD OVER CRL VOR CLBING SLOWLY TO FL370 WAS ASSIGNED HDG 070 DEGS TO FACILITATE 2 NWBOUND MLG'S AT FL350; ONE OF WHICH WAS ASSIGNED A HDG OF 285 DEGS BEHIND HIM AT FL350; THE OTHER ON A NE HDG FOR CLB TO FL350 FOR MLG SE AT FL330. WHEN THE NEBOUND TFC LEVELED AT FL350 HE WAS TURNED TO A 270 DEG HDG TO GO BEHIND ACR X; A CPR Y WHO WAS ALSO EBOUND WAS ASSIGNED A 070 DEG HDG TO PARALLEL ACR X. THE ACFT THAT WAS ON THE 270 DEG HDG AND THE ACR X STILL DID NOT HAVE THE REQUIRED 5 MI LATERAL SEPARATION WITH EACH OTHER SO ACR X WAS TURNED TO A 360 DEG HDG AND THE MLG TO A 250 DEG HDG TO KEEP 5 MI LATERAL SEPARATION. THIS 250 DEG HDG MADE HIM TFC WITH THE OTHER ACFT WHO HAD BEEN TURNED TO A 360 DEG HDG TO FOLLOW THE FIRST MLG AT FL350 FOR SPACING TO MSP. THERE AT THIS TIME WERE SEVERAL OTHER ACFT ON FREQ WHO WERE ON HDGS FOR THE SPACING TO MSP. AS I WAS ALLEVIATING THE SIT WITH THE 2 MLG ACFT AT FL350; ACR X HAD BECOME TFC WITH THE CPR Y WITH A RAPID RATE OF CLOSURE. I TRIED TO TURN CPR Y TO A 360 DEG HDG AND ACR X TO 180 DEGS BUT SEPARATION HAD BECOME LOST.