Hugo, the children born earlier are shown to have been born in Bangor in some cases.
On the 1841 census they have children born before Margaret as follows:
Mary Philips (cannot see her age)
John Philips age 9.
Ellen Philips age 6
Daniel Philips age 3.
In the 1851, the children with the household born before Margaret are:
John Philips, age 18, Miner, born Bangor, Caerns.
Elinor Philips, age 16, Scholar, born Bangor.
There is a tree on Ancestry which shows children born pre 1840 as follows:
John Philips, born either Llandudno, or Bangor, in 1832/33. Died 3 March 1867, Valencia, Spain.
Ellen Philips born Bangor, 18 September 1834, baptised 26 June 1838, Llangystennin.
Elinor Philips, born 1835, Llandudno, or Bangor, Baptised 26 June 1838 Llangystennin.
Robert Lloyd Philips born 4 July 1835, Llandudno, baptised 26 June 1838, Llangystennin, died 1841 Conwy.
Daniel Philips born 1838 Llandudno. Died 3 March 1867, Valencia, Spain. It says "Extreme Clipper Sultana" for his place of death.
There is a curious entry after the birth of Margaret which shows "January 1841, birth of half sister". There are no details given.
Some of the children seem to have been baptised as a sort of job lot in 1838.
Helig.