In summary of where I think we got to on the other post, we had
Thomas Snr and Jame Milligan's marriage in 1840 Liverpool
Thomas and Janet in 1841 census in Liverpool
Thomas in 1851 in Everton, Lancs. and Janet in 1851, with Janet visiting her father in Kirkcudbright
Thomas and Janet in 1871, likely entry in Liverpool
The gaps from the last post were:
Confirmation of Thomas and Janet's fathers' names from their 1840 marriage to let you work back in confidence, although likely family for Janet Milligan already working back from that 1851 census entry and possible Old Parish Register entries.
Any trace of Thomas Jnr.'s birth or christening entry in the Old Parish Registers, likely in Kircudbrightshire.
1861 census for the family including any further details on Thomas Jnr and William, apart from the likely 1851 census entry we had back in Kircudbrightshire.
Monica