4./JG 54, where was it in January-April 1944

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Hi
I'm trying to track down where the 4./JG 54 was from January to April 1944.
One sources says:
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"III.JG 54's withdrawal from Russia was the result of a decision by Adolf Galland, the General der Jagdflieger, to exchange one complete western based Jagdgeschwader with another from the eastern front.
The two units selected were JGs 26 and 54.
...
But either Galland thought better of it - or more cautions minds prevailed upon him so to do - for the scheme was abandoned after just one Gruppe, plus one additional Staffel, from each Jagdgeschwader had made the move."
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There 4./JG 54 operated under III./JG 26 in the west from 2.43 to 6.44, other sources also mention that parts were used to form the new IV./JG 54 in July 1943 and that the Staffel formed the new 15./JG 54 in August 1944 when JG 54 moved to a new 4 Staffeln per Gruppe structure.
So far so good, but another sources list the Staffel at Luftflotte 1 on 10th January 1944 but that covered the area of Heeresgruppe Nord on the East front at that time.

So long text short question, where was the 4./JG 54 from January to April 1944?