I found more than one Moses Seiver in England, can you give approx BMD and where? Do you know his parents names or any siblings.

Moses Sevior
Birth date 1750
city, Hampshire, England
Moses was married to Mary Over and they had a son Moses (below).

Moses (William) Seiver
Born 1778 Ellingham, Hampshire, England
Christened Aug 1778 Ellingham, Hampshire, England
Died 1824 Kent Street, Southwark, Surrey
Buried 27 Apr 1824 St George, Southwark
Father Moses Sevior ( - ) Mother Mary Over (1752- )
Marriage 6 Sep 1803 St Clement Danes, Westminster, London
Wife Eleanor Pritchard
Born 1776 London, Middlesex
Died 17 May 1841 2 Delph Street, Southwark, London
Cause of Death Decay

Children
1 M Henry Over Seiver
Born 25 Jun 1805 Bermondsey Street, Bermondsey, Surrey
Christened 18 Sep 1805 St Mary Magdalen, Bermondsey, Surrey
Died 13 Jan 1879 Walworth Infirmary, Surrey

2 M William Over Seiver
Born 13 Oct 1807 Bermondsey Street, Bermondsey, Surrey
Christened 16 Oct 1807 St Mary Magdalen, Bermondsey, Surrey

Spouse Ann Christian Clark ( - ) 16 Dec 1839 - St John's Waterloo, Lambeth, Surrey
Spouse Elizabeth Pearman ( - ) 25 Dec 1833 - St Trinity Church, Newington St Mary, Surrey
3 F Mary Ann Seiver
Born 27 Mar 1810 Bermondsey, Surrey, England
Christened 28 Oct 1810 St Mary Magdalen, Bermondsey, Surrey

4 F Eleanor Elizabeth Seiver
Born 24 May 1816 Southwark, Surrey, England
Christened 30 Jun 1816 St George The Martyr, Southwark, Surrey
Died 22 Nov 1829 Dobbs Cross, Kent Street, Southwark, Surrey

5 M Charles Seiver
Born 10 Feb 1818 London, Middlesex
Christened 28 May 1820 St George The Martyr, Southwark, Surrey
Died 11 May 1892 Gorleston, Yarmouth, England
Cause of Death Exhaustion, Chronic Peritonitis, Right Inquinal Hernia

6 M John Seiver (my GGGrandfather)
Born 14 Feb 1820 Southwark, Surrey, England
Christened 28 May 1820 St George The Martyr, Southwark, Surrey
Died 12 Jan 1878 Mercer Street, Geelong
Cause of Death Disease of Lungs and Heart, 10 Months
Buried 14 Jan 1878 Geelong Eastern Cemetary
Spouse Ann Williams (1823-1901) 27 Nov 1842 - St George The Martyr, Southwark, Surrey