Thanks jonwarm

Dublin almanac and general register of Ireland 1840
"Mitchell Wm. & Son, confectioners to his Excellency the Lord Lieutenant, 10 Grafton street, and Grafton house, Fairview, Clontarf"
https://babel.hathitrust.org/cgi/pt?id=pst.000053089823&seq=505&q1=mitchell&start=1ARTISTS’ WAREHOUSE, 2. GRAFTON-STREET, corner of Nassau-street. XT’ KATES and SON solicit, most respectfully, ..
... to No. and the 3d the Plates. tickets one shieling each, at M
r. Mitchell’s, Confectioner, 10, Grafton-street, and Grafton House, Fairview Avenue, Northstrand • Mr. Dignam, Silk Manufacturer, 100, Brilain-street; Mr. Reigb, Ballybough-bridge, North-strand ...
Published: Wednesday 30 December 1835
Newspaper: Saunders's News-Letter
County: Dublin, Republic of Ireland
Type: Article | Words: 497 | Page: 3
It seems their first commercial address was 36 Nassau Street (interestingly there was a George Mansfield, bookseller, at 35 Nassau Street in 1828, any connection to the Mansfields?)
Their second commercial address was 10 Grafton Street and their residence was Grafton House, Fairview, Clontarf.
I think Robert was living at his father's house until his marriage in 1844 (when all the properties were in his brother's -George Patrick- name as per their father's will).
Apparently they all lived in the same household, given that Robert's first child (Sarah Ann) was born at Windy Arbour in 1846, and after George's death in 1847 this property was in the name of Mrs. Mitchell, George's widow Sarah. (Did George sell the Fairview country house, contrary to his father's codicil?)
Some newspaper ads show that George's brother (Robert) was working with George at 10 Grafton Street before George's death, as they refer to Messrs. Mitchell, confectioners, and about one year before George's death they refer to Mrs. Mitchell, confectioner (let's remember that both George and his father William died after suffering from a 'lingering' illness, any connection to the genetic disorder hydrocephalus that claimed the lives of 5 male infants?).
By that time, 1847, Robert Mitchell is at 168 Rathmines Road, Haroldscross East, and 29 Rathmines Road, Haroldscross East, in 1850 (Did he inherit anything after George's death?)
In 1851-52, Robert Mitchell, confectioner, is at number 68 Rathmines Road (Fortescue Terrace), when his youngest son (as far as we know), Alfred Mansfield Mitchell was born.
What happens to the family until his first daughter Sarah Ann married Hugh Maguire in 1870 at Belfast? (and as aghadowey has pointed out at
https://www.rootschat.com/forum/index.php?topic=894764.msg7692806#msg7692806 Robert's occupation is not given)
Edited: I have just noticed that one of the witnesses of this marriage is Elizabeth Mary Mitchell. Is this her mother??
It's a long period of time without any (known) references in the newspapers.