Hi Sandra,
Well, here they are in the 1891 census - Amos and Ann with Ann's Prosser children and a new son by Amos.
(please any errors in the place names - I'm really bad with Welsh!)
RG12/4431 Folio 94 Page 34
Tir phil, Gelligaer, Glamorganshire, Wales
Address: 20 Railway Terrace
Amos Rogers, Head, 29, Coal Miner, b. Monmouth Llanithel
Ann Rogers, Wife, 39, b. Monmouth Bedwellty
Annie Prosser, Daur, 18, General Servant Domestic, b. Glamorgan Gelligaer
Edward H Prosser, Son, 17, Coal Miner, b. Glamorgan Gelligaer
Frances Prosser, Son, 14, Coal Miner, b. Lancashire Aspool
Margaret Prosser, Daur, 11, Scholar, b. Lancashire Goldbourne
William Prosser, Son, 5, b. Monmouth Mynyddeslwyn
David W Rogers, Son, 2, b. Monmouth Mynyddeslwyn
Wow - can you imagine being the step father of an 18-year-old at age 29?
If you order their marriage certificate using the reference number I gave you above, it will show their fathers' names. That will help you trace them back in earlier census records.
I'll see if I can find them in earlier censuses...
MJP