Hi Karen,
I'm a Portlaoise man, 'born and reared' and my uncle is 91 years and still going strong, but neither of us, and others, remembers a Dollard Shop in Portlaoise.
Around the time frame you sat, 1920's there were three 'little' shops in Portlaoise,
Daltons, Rogers and Donnelly of Coote St.
Checking my records for Portlaoise cemetery, 1897-1990 the first DULLARD burial is in 1906, Mary (50)
1917; Dullard Patrick (62)
1932; Dullard John (40)
1961; Dollard Sarah (30)
1963; Dullard Catherine; (75)
1977; Dollard Andrew; (78)
1983; Dollard Mary; (87)
1990; Dollard Annie; (96)
1990; Dollard John; (66)
You do not say the name of your grandfather and we might be able to assist with that.
Regards,
Jack