(if (and (tblsearch "LAYER" "[color=red]My-Layer-Name[/color]") [color=dimgray];;; Only one layer name here [/color]
(setq ss
(ssget "_:L" '((0 . "INSERT") (2 . "[color=blue]Block1,Block2,Block3[/color]")))) [color=dimgray];;; A list of block names separated with a comma [/color]