the museum will almost certainly answer, very politely, that they do not do any research for visitors, they will suggest that you employ a local researcher for this - on your visit they will help you find the material requested and may suggest further lines of research.
Gilbert Corlet (the part owner of sheep) was almost certainly a next door neighbour in Ballacorleod/ballacorlett - his will dated 19 jul 1782;ballacorlett;gson john corlett;wife jane [corjeag] - born 1711 s/o Gilbt corlet + jony mcBooy - it is possible that ann corlett is his aunt but I havn't looked in detail at this line.
I have no idea where you get info re foster children unless you can find then as under age orphans in a parent's will, in some cases it will state which supervisor (a near relation) is maintaining the child.