I have my own private McAlonan list with about 12 searchers. In making a compendium of their ancestors, the ones that seem to fit the closest with yours are the following:
1. Alexander McAlonan b. abt 1810, m. Catherine Corrigan
2. Robert McAlonan, b. Carrickfergus, Antrim, 1837, m.
Elizabeth Hendry in Port Glasgow, Renfrewshire. She
born in Ballycastle, Antrim;
3. William John McAlonan, October 19, 1861 Port
3. Ann McAlonan, abt 1865
3. Robert James
3. Daniel Alexander
3. Henry McAlonan, m. Mary Rice
4. Selina McAlonon, m. ? Healy
5. Maureen Healy
4. Robert McAlonan, m. Elizabeth McKay
5. Mary Jane Rice McAlonan, September 19,
5. Margaret McKinney McAlonan . b. July 28,
3. Elizabeth McAlonan
2. Patrick McAlonan, b. 1835, m. Sarah Dimond, Nov. 8,
1858, Port Glasgow
3. Alexander McAlonan
3. Catherine McAlonan
3. Sarah McAlonan
While I realize your John is not listed, could he be a brother of this Robert?
Unfortunately, the person who submitted this drops in and out of his email address as he is a seaman. He is currently off the list so I can't put you in touch with him.
If you want more particulars, let me know and I will see what else he wrote a couple of years ago.