Dear Pam:
Thank you for your query.
I have had a look for Margaret Melody (with spelling variants) on the Roots Ireland database for the year of birth/baptism 1840 with a father named Patrick, and the only one that I have found is below:
Margaret Malady
baptised 4 March 1838 Newbridge, County Kildare. Residence was Kilbelan.
Father: Patrick Malady
Mother: Ann Flood
Sponsors: Michael Connelly and Bess Leeson.
The original page in the Newbridge baptism register is here: https://registers.nli.ie/registers/vtls000634531#page/20/mode/1up The entry is located at the left top of the page.
There isn't any other child born to this couple named Ellen that I was able to find.
I did find a baptism record for an Ellen Melady born in 1832 in West Meath. Here are her details:
Ellen Malady baptised 8 February 1832 Tubberclair, County West Meath.. No residence given.
Father: Patrick Malady
Mother: Mary Shanly
Sponsors: Michael Malady and Ellen Gorwmly.
The original page in the Tubberclair baptism register is here: https://registers.nli.ie/registers/vtls000635201#page/22/mode/1up This entry is located at the left bottom of the page,and it is much clearer to read than the entry for Margaret.
The parish of Tubberclair is also known as Kilkenny West and this parish is certainly closer to Counties Sligo and Mayo as you stated your Ancestry DNA indicates that your ancestors may have been from those areas.
Either place may be a starting point for your research. If you have not done any research on Ellen, it might be worth trying to find further documentation on her which may give you at least a County. Please get back to us if you have any questions.
The very best of luck.
Kind regards,
Jane