Mac Donald - Agnes - Alexander

Am seeking possible relatives in Glasgow (Renfrew) Scotland. My grandmother, Agnes MacDonald, was born there in 1875 or 1876 and came to New York about 1896. Married Jacob Schrack there Oct 1897. Her parents were Alexander MacDonald and Agnes Thomson Wilson and she had one sister, Grace. Possible other siblings: Kenneth, Anna, Alexander who probably all remained in Scotland. Pictures I have of that family show a large group so I assume that I have numerous second cousins. Would like to hear from anyone who might help me make the connection.