John McCormack married Christine Cullen in Cavan on 24 September 1879, they were both described as of the 'Theatrical Profession':
https://civilrecords.irishgenealogy.ie/churchrecords/images/marriage_returns/marriages_1879/11075/8052659.pdf
Possibly two more baptisms for children of this couple (ie. the parents' names match), they are from transcript, I haven't seen the original registers, so they come with that big health warning:
- New Ross RC parish, Co. Wexford, Patrick John McCormack, baptised 16 March 1882 (birth 10 March), sponsors John Dalton and Jane Dalton;
- Clonbroney RC parish, Co. Longford, William McCormack, baptised 27 March 1885, sponsors Thomas Shaw and Mary A Cullen, a comment attached to this transcript says 'may have been travelling actors histrioni in forma panpstasis'.