Grace died in 1840, and was buried at Wookey on 5 Apr 1840 aged 35. No Wookey baptisms before 1813 so can't see if she was baptised there.
There is a Robert VAISEY widower marrying at Shepton Mallett on 27 Dec 1842 to a Sarah LOCKYEAR widow. Robert's father is listed as Levy VAISEY in the Shepton Mallet marriages. The index on FreeBMD lists Robert as VOISEY. This would appear to be your Levi/Robert.
This Robert in 1851 is down at Levi
Wookey, Somerset
Levi VOISEY, head mar 50, Pauper (Ag Lab), born Bath, Somerset
Sarah VOISEY, wife mar 47, born Glastonbury, Somerset
John VOISEY, son 13, born Wookey, Somerset
John LOCKYEAR, son 12, born Easton, Somerset
Ellen VOISEY, dau 3, born Wookey, Somerset
Benjamin LUTSOM, lodger wid 84, Pauper (Ag lab), born Wookey, Somerset
HO107/1934 146 16
But see he was Robert in 1841. The same in 1861, where he says he was born Wookey
Frederick belongs to Levi/Sarah, Ellen to Robert/Sarah, and the others to Levi/Grace.
Ian C