1. For Mary Ann B 1860-1864, I found 4 B rcds: 1-1860 Roscommon, 1-1860 . 1-1862 . and 1-1864 all in Leitrim.
2. For James B 1862 +/- 2 yrs, I found 7 B rcds: 4-Leitrim, 3-Roscommon.
3. For Patrick B 1863 (exact), I found 0 B rcds in either Leitrim or Roscommon, but 1 in all Ireland.
4. For Jane B 1866 (exact), I found 0 B rcds in either Leitrim or Roscommon, but 3 in all Ireland.
5. For John B 1857 +/- 3 yrs, I found 3 B rcds in Leitrim/Roscommon.
6. For Elizabeth B 1853-1868, I found 3 B rcds in Leitrim/Roscommon.
7. For Owen, an age of 77 in 1901 implies a DOB of 1824 +/- 1 yr. For this range, I found 0 B rcds in all Ireland. It is likely that this event wasn't rcd'd, or the rcd didn't survive.
8. For Celia, her implied DOB is 1835. Since you didn't list her maiden name, I can't search. It may be she was a 2nd wife. Suggest you try to find her maiden name. This MIGHT be possible by finding her DOD and using this to request a Death Certificate from the General Register Office at http://www.groireland.iehttp://www.groireland.ie.