I am not aware of any authentic, well‑documented Jain historical account that matches exactly this description:

• three Jain idols found in a particular person’s house,
• whose grandfather knew about the hidden idols as a “family secret” passed down from ancestors,
• specifically connected with a “Mana village”.

This sounds like a local or family oral story or a recent news incident, not a classical Jain scriptural or tirth‑history narrative.

In Jain history we do have many similar types of incidents:

• Idols hidden underground or inside houses during times of invasion or fear of theft.
• After many generations, someone receives a dream, intuition, or remembers an old family tradition and the idols are rediscovered.
• Such rediscoveries sometimes become the starting point of a new derasar or tirth.

You will find many traditional Jain stories where ancient idols are found during digging, construction, or by following a dream/indication, for example some Parshvanath idols and tirths described on JainKnowledge.com (like Jirawala, Shankhla Parshvanath, Mandar Tirth, etc.), where murtis were recovered from underground and then installed in a temple.

But for the specific case you mentioned (Mana village, three idols in one house, grandfather’s secret), I do not have a reliable Jain source that clearly records this as a recognized tirth‑story.

So, from the perspective of Jain Dharma:

• Such a story can be respected as a local vaarta (tradition).
• Spiritually, the important point is the reverence for the idols, proper pratishtha (if needed), and shuddha bhakti towards the Tirthankaras, rather than the sensational aspect of “secret idols”.

If you have more concrete details (name of village, district, or the Jain tirth now associated with those idols), then it might correspond to a known tirth whose formal name is different from “Mana village,” but with the information given, it does not match any standard, documented Jain tirth‑katha I can confidently identify.