[R-meta] aggregate data continues outcomes

I do appreciate it if you direct me how to aggregate the 2 groups below. 
This study has 3 arms, comparison between A , B, and C.
Group 1: A compare to B 
Group 2: A compare to C
I need to aggregate theses 2 groups

								
	M	SD	N	M	DD	N		
Group1	1248.0	698.0	15	2381.0	1313.0	15		
Group2	1248.0	698.0	15	1878.0	720.0	15		

Many thanks in advance,
Homa