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The church marriage record for the 1901 marriage shows Ellen's father as Thomas Bowen. If she was originally a Cusack, it would seem that her father's name would be a Cusack. The civil marriage record is not online but I did locate the index record. Using the index record, you can write to the General Register Office and get a copy for around 4 euros. The record should show her marital status at marriage-- widow or unmarried. If you need instructions let me know.
I also looked for a civil marriage record for an Ellen Cusack to someone with the surname Bowen and no record came up.
Regarding possible living descendants, you can try the online Irish phone book which is a partial list of phone users. Make sure you use the Residential TAB.
Let me know what questions you have.
First name(s)EllenLast nameBowenRegistration year1901Registered Quarter/YearJan - Mar 1901Registration districtKilmallockVolume5Page259MarriageFinder™Ellen Bowen married one of these people
Thomas Leary, Michael Dunlay, James Walsh, Michael Dunlea, Maurice CreminCounty-