I hope some of this helps?
JAMES CAMPBELL married JANET GRAY 19/10/1799 Paisley Middle banns also at Paisley Burgh or Low 18/10/1799
Children Paisley High Church JAMES 9/04/1802, CHRISTIAN 14/03/1804.
No other records on SP for James Campbell & Janet Gray except HUGH 16/07/1817 = Abbey
No 1851 census for James senior and Janet and no death records on SP for Paisley prior to Statutory Registration in 1855.
There is a death of a James Campbell age 71 in 1855 but I do not think it is he. That James appears with his family in 1851.
This is likely to be James 1802 above = 1851 West Campbell St. abode Martyrs Qs
CAMPBELL James Head 48 Hand Loom Weaver (Wool) RFW Paisley
CAMPBELL Mary Wife 35 RFW Paisley
CAMPBELL James Son 9 Weaver's Drawboy Assistant RFW Paisley
CHRISTIAN CAMPBELL Likely married WILLIAM BLAIR 11/08/1820 Paisley High Church
MARION BLAIR Daughter WILLIAM BLAIR/CHRISTIAN CAMPBELL 30/03/1828 Abbey
The census below is unlikely to relate to the above, even if Janet’s age has been rounded down to 50 from 54 she would only have been 12 when married, unless the original census has been wrongly transcribed?
The only link seems to be Hugh, even his ages do not fit too well, however see below.
1841 census in West Campbell St (Already posted) abode Martyrs Qs
CAMPBELL James 60 Cotton Hand Loom Weaver RFW
CAMPBELL Janet 50 RFW
CAMPBELL William 26 Silk Hand Loom Weaver RFW
CAMPBELL Andrew 24 RFW
CAMPBELL Cunningham 22 RFW
CAMPBELL Hugh 20 RFW
CAMPBELL Janet 18 RFW
Hugh reappears in 1861.
West Campbell St abode Martyrs Qs
CAMPBELL John Head 52 Harness Weaver RFW Paisley
CAMPBELL Anne Wife 51 Pirn Winder RFW Mearns
CAMPBELL Janet Dau 17 Harness Weaver RFW Paisley
CAMPBELL Robert Son 15 Harness Weaver RFW Paisley
CAMPBELL Annabella Dau 11 Weavers Asstnt RFW Paisley
CAMPBELL Hugh Lodger 36 Harness Weaver RFW Paisley
Good luck, Colin