acolar

A rare, technical term from heraldry: to place two coats of arms side by side, joined at the edge (as when a married couple's family arms are combined). Outside heraldic or specialist writing you'll essentially never encounter it.

• El escudo acola las armas de ambas familias. — The coat of arms joins the arms of both families side by side.
• En heráldica, se acolan los blasones de los cónyuges. — In heraldry, the spouses' coats of arms are placed side by side.
• El diseñador acoló dos emblemas en el nuevo sello. — The designer joined two emblems side by side in the new seal.

There's no everyday mistake to flag here — this is a specialist heraldry term most native speakers never use or need; don't reach for it as a fancy synonym for unir or juntar in ordinary writing.