Using MapIndexed rather than Replace
MapIndexed
Replace
data // MapIndexed[{Around[First@#1, errors[[#2]]], Sequence @@ Rest@#} &]
Perfect thank you
Hi Henry,
How about
Transpose[{data, errors}] /. {{a_, b_, c_}, d_} :> {Around[a, d], b, c} (* {{a1±e1,b1,c1},{a2±e2,b2,c2},{a3±e3,b3,c3}} *)