Neville Raschid's film, White Chamber, is being launched at the Edinburgh International Film Festival and the Rev Margaret MacGregor will be welcomed as a guest of honour.
Mr Raschid, 61, grew up in India and East Pakistan, in what is now Bangladesh, and has strong family ties to the Kirk's Mission in Calcutta dating back to the 1930s.
Miss MacGregor, originally from Irvine, spent her career in India as a missionary and gave practical help to Mr Raschid's family following the tragic murder of his father by insurgents whilst he was working in a tea plantation.
The two haven't met since Miss MacGregor, who now lives in Edinburgh, provided the blessing at his wedding in 1990.
Mr Raschid's mother, Dolly, spent her early life at St Ninian's, a school and orphanage run by the World Mission Council in Cossipore, in the north of Calcutta, as she was born illegitimate.
Alexa Scott, who headed the school from the 1930s until the 1960s, was approached to provide a stable upbringing for Dolly after her mother was ostracised by her Indian family.
Mr Raschid said: "My mother was mixed race which in the 1930s was very rare.
"My grandfather was a high ranking white British inspector general of police and had a liaison with a high caste Hindu woman.
"My grandfather asked if Alexa Scott would raise Dolly - St Ninian's became her home", he said.
After St Ninian's Dolly met Paul Raschid Sr., a Bengali who had also been adopted by a missionary couple, the Ewarts, and the two later married.
Sadly, after a happy start and three children together, Paul Raschid Sr. was killed in the former East Pakistan.
Family photos from the early 60s including on the steps of the manager's bungalow, Rajnagar Tea Estate with Neville, in the centre of the photo, his brothers Andrew and David, and his parents.
"He was gunned down by Marxist-type insurgents", Mr Raschid said.
As a result Dolly turned to the Church of Scotland for help.
"We were given sanctuary by World Mission once again", he said.
By this point Alexa Scott was about to retire but Miss MacGregor, who Mr Raschid refers to as his 'Aunty Margaret', had recently arrived at the Mission.
Miss MacGregor, who spent 35 years of her career in India and published the first ever guide to learning Greek in Bengali, supported the family in the immediate aftermath of his father's death.
She said: "It was a difficult time for the family.
"Neville's mother regarded Cossipore as her home which is why she came back."
"I'm looking forward to seeing Neville and his son.
"I haven't seen him since his wedding."
"It's a great thing for his film to be premiered at the film festival."
Paul Raschid Sr. with his foster mother Edith Ewart in 1962. Alongside her husband Douglas, the Ewarts were missionaries in Rajshahi which is now in Bangladesh.
His father's foster parents the Ewarts also supported Mr Raschid, and he finished his education in the UK at Gordonstoun School in Moray followed by Cambridge.
Decades later, Mr Raschid remembers the connection his family shares with the Church of Scotland fondly.
"It's a blessed story - I feel very blessed" he said.
Mr Raschid, who lives in Ealing on the outskirts of London, became an accountant before setting up a company as a film producer.
White Chamber is a collaborative effort with his son, Paul Raschid Jr. who wrote and directed the film.
It will be shown in Edinburgh at 8.30pm on Thursday 21st June at Cineworld and at 6.10 pm on Friday 22 June at the Vue Omni.