Father Nicholas Clarke, 49, and sons Toby, 23, and Darren, 18, of Dacre Road, Herstmonceux, had all pleaded guilty to public order offences committed in a marquee at the Sundial Restaurant in Gardner Street on August 8 last year.
Hove Crown Court heard that just before midnight, Darren and Toby walked uninvited in to the restaurant and were asked to leave by guests.
They became abusive and were ejected but returned a short while later with their parents. The situation escalated and threats were made with a baseball bat.
At Monday's sentencing, Judge Cedric Joseph told the three men their behaviour was 'absolutely disgraceful'.
Nicholas Clarke was sentenced to eight months in prison for possessing a firearm and was given a £400 fine and ordered to pay £150 costs for the public order offence at the wedding reception.
Toby was also given eight months for possession of a firearm and four months, to run consecutively, for a public order offence.
Darren Clarke was sentenced to 12 months in a young offenders' institution for affray and three months - to run concurrently - for possession of an offensive weapon, the baseball bat.
Mum Jeanette, 46, had pleaded guilty to charges of obstructing police, resisting arrest and common assault.
She was given a 12-month conditional discharge, fined £100 and ordered to pay £150 costs.
Judge Joseph, speaking to Mr Clarke and his sons, said it was clear they had wrecked an otherwise perfectly happy wedding day.
Afterwards, Chief Inspector Julia Pope, district commander for Wealden, said, "This is a fantastic result for the community of Herstmonceux.
"I take a firm stance against anti-social behaviour and will not tolerate any section of my community being subjected to this sort of disgusting action."