No service record survives but his full placements were:
1/A & SH - 9751
12/A & SH - same number
11/Scottish Rifles - 27436
1/Scottish Rifles - same number
15/R.Scots - 51427
12/R.Scots - same number
This is what the LLT says about them:
A & SH
1st Battalion
August 1914 : in Dinapore, India. Returned to England, landing Plymouth on 19 November 1914. Moved to Winchester and came under orders of 81st Brigade in 27th Division.
20 December 1914 : landed at Le Havre.
Later moved to Salonika, arriving 12 December 1915
12th (Service) Battalion
Formed at Stirling in September 1914 as part of K3 and came under orders of 77th Brigade in 26th Division. Moved to Codford St Mary and went into billets in Bristol in November 1914. Moved to Sutton Veny in April 1915.
20 September 1915 : landed at Boulogne but soon moved and by November 1915 was at Salonika.
S.Rifles
11th (Service) Battalion
Formed at Hamilton in October 1914 as part of K3 and came under orders of 77th Brigade in 26th Division. Moved to Codford St Mary but by December 1914 was in billets in Bristol. Moved to Warminster in February 1915 and Sutton Veny in April.
Landed at Boulogne on 20 September 1915 but sailed for Salonika in November 1915.
1st Battalion
August 1914 : in Glasgow. Left by train for Southampton late on 13 August 1914. Next day, embarked on the SS “Caledonia” and sailed.
15 August 1914 : landed at Le Havre as Lines of Communication troops.
22 August 1914 : came under orders of 19th Infantry Brigade, which was not allocated to a Division but was an independent command at this time.
12 October 1914 : transferred with Brigade to 6th Division.
31 May 1915 : transferred with Brigade to 27th Division.
19 August 1915 : transferred with Brigade to 2nd Division.
25 November 1915 : transferred with Brigade to 33rd Division.
R.Scots.
15th (Service) Battalion (1st Edinburgh)
Formed at Edinburgh in September 1914 by the Lord Provost and City, although some 550 men were recruited in Manchester and for this reason the Battalion is sometimes referred to as the Manchester Scottish. Moved to Troon March 1915.
June 1915 : moved to Ripon and attached to 101st Brigade, 34th Division. Moved to Sutton Veny September 1915.
Landed at Le Havre 8 January 1916.
16 May 1918 : reduced to cadre strength after suffering heavy casualties.
17 May 1918 : attached to 39th Division.
14 August 1918 : disbanded in France.
12th (Service) Battalion
Formed at Edinburgh, August 1914, as part of K1.
August 1914 : attached to 27th Brigade, 9th (Scottish) Division and moved to Bordon.
Landed in France May 1915.
You can see that his first 3 Batts. were all in Salonika at the same time which is when he probably transferred from one to the other.
He must have gone to France with the 1/A & SH as they were the only Batt. there at the time he qualified for his 15 Star (6/3/15).
At some point he returned to France & ended his service with the 12/RS this was probably after the 15/RS was disbanded.
If you can give the exact dates on the birth certs. against which Regt./Batt. he was in we might be able to tweak the dates of transfer.
1 Abraham Greer + 1 Abraham John Greer. He died & was from Ireland so not him.
This leaves:
Abraham Greer 16/HLI no. 23593 & 5/HLI no. 291985 (5/Batt. were TF hence the 6 digit number).
Not correct his 2nd. unit was 5/Gordon Highlanders no. 291985. They were also a Territorial Force Batt.