What makes you think this is the correct James Power? what were the names of your Mary Jane's siblings that went to America?
James Power and Mary McConnell had several children according to submitted records in IGI (
www.familysearch.org)-
1. Jane born 5 Jan.1869 Mileford [Milford?], Co. Donegal
2. Mary Ann born 7 Apr.1871 Carrowkeel/Carronkeel, Co. Donegal
3. John born 6 June 1873 Carronkeel, Co. Donegal
4. Letitia born 17 Sept.1875 Crowhan, Co. Donegal
5. Alexander born 8 Jan.1877 Carrowkeel, Co. Donegal
6. Alice born 22 Dec.1879 Carrowkeel, Co. Donegal