Anne C,
I checked further, but cannot locate any Alice Brady, daughter of Edward Brady & Margaret Brady on the subscription website www.rootsireland.ie anywhere in Ireland during the period 1816 - 1826, even searching for both parents individually.
Similarly, I could not locate any Edward Brady with a wife named Margaret marriage prior to 1824, nor any Edward Brady marriage prior to 1826 in County Longford. However, only 4 of County Longford's 23 RC Parishes have records commencing in 1820 or earlier.
I see Alice Brady Dittoe, aged 29, born in Ireland, with her husband and three children recorded at her father Edward Brady's house, Reading, Perry, Ohio in the 1850 U.S. Census.
I do not see any record of Mary (Anne) Brady in the 1850 U.S. Census but she appears again at Reading, Perry, Ohio with her parents in the 1860 Census.
About half of County Cavan's 1821 Census still exists, and is available at the following website:
http://census.nationalarchives.ie/search/results.jsp?searchMoreVisible=…;
However, I have not been able to locate any Edward Brady & Margaret Brady couple in these records. Nor have I been able to locate any Alice Brady under the age of 10.
Finally, I also see the 1899 Wills of Margaret Brady & Catherine Brady, who both died in 1901, mentioning their sister Clara Brady Kintz.
It looks like you will not be able to locate any further information on your ancestors before you arrive in Ireland in September.
On account of the Granard address given for Mary Anne Brady's baptism in 1823 you should concentrate on the Town of Granard during your visit.
St. Patrick’s Cemetery, Granardkill is the old graveyard & old Church ruin – the site of Old Granard Town burned by Edward Bruce in 1315 is opposite this cemetery.
Granard Motte overlooking the Town of Granard, dating back to Norman times.
Knights and Conquests Heritage Centre (check the opening times).
Greville Arms Hotel (if open, as once belonged to The Kiernan Family - connected with Michael Collins, Irish Freedom Fighter, whose fiancee was Kitty Kiernan) & neighbouring Market House, built c1785.
St Mary’s RC Church (1867).
Cnoc Mhuire Secondary School (Site of Granard Workhouse 1842 - 1932).
The neighbouring Towns and Villages are: Abbeylara, Edgeworthstown and Ballinalee.
Have a look at the Granard Historical Society's Facebook page:
https://www.facebook.com/GranardAreaHistoricalSociety/
for more to do and see around Granard.
Hoping this helps further,