They went from busking at Tampines MRT station to performing at the floating platform at Marina Bay for the National Day Parade (NDP) this year.
Now, Mr Mashruddin Saharuddin, 64, and his son Nizaruddin Mashruddin, 27, have also been to the Istana to meet President Halimah Yacob.
They were among some 1,300 guests at the National Day reception hosted by Madam Halimah at the Istana yesterday. They were there along with other inspiring Singaporeans featured at the parade on Thursday. Prime Minister Lee Hsien Loong and Emeritus Senior Minister Goh Chok Tong and their wives also attended the reception.
The guests, who included ministers, MPs, senior civil servants, grassroots leaders and representatives from volunteer groups and arts and culture groups, were treated to singer-songwriter Charlie Lim's performance of this year's National Day song, an updated version of the 1987 classic We Are Singapore.
Mr Mashruddin said: "I am happy to be here. I came here a few times in the past, but so much has changed now. I wonder if there are still butterflies outside."
He had been to the Istana when he was 15, as part of a Boy Scouts co-curricular activity where participants did some form of voluntary work for a week. He cleaned and polished brassware at the Istana.
Mr Mashruddin, who was born blind, said that even though he could not see the huge crowds at the NDP, he could feel their energy.
"It is my biggest task, and yet it also feels the same as my regular busking. I am always nervous, and I don't like crowds," he said with a laugh.
For Mr Nizaruddin, it was his first time visiting the Istana and meeting a president. "I never thought I would be here. I never even thought I would make it on television," said Mr Nizaruddin, who started performing with his father when he was 13. Their rendition of the well-loved song, Home, at the NDP went viral online, and many gave them the thumbs up on social media, saying that the performance had touched them deeply.
Mr Nizaruddin said: "I went to sleep after the parade and woke up with so many messages from people who said they teared up because of our performance. People congratulated me and wanted to follow me on Instagram or be my friend on Facebook."
He added that people recognise him in public now, and they wave and want to take pictures.
But what makes him happiest are the messages from people who have supported him for more than a decade and followed the performances of him and his father at Tampines MRT station, where they busk nearly every day. "They have known me since I was a boy. This whole thing is new and unexpected for me, but it is such a good feeling."
Former Olympic sprinter Mary Klass, 83, said it was also her first time meeting Madam Halimah. "I feel so honoured to be here. After yesterday, a lot of people said they were inspired by my story. I stood there watching the parade, and I say it is the best one I have seen."
Mr Veera Sekaran, 56, founder of green design firm Greenology, said he was overwhelmed by being featured at the parade and then being invited to the reception. "I had mixed feelings yesterday. I was happy to tell my story, but also sad because it reminded me of my struggles. I cried," said Mr Veera, who overcame childhood poverty to do well in school.
"But I also think this narrative is important to us as Singaporeans because society often looks down on people's failures. We are 'kiasu' and embarrassed to share such stories, but we need to overcome stigmas."