Is it permissible to conceal the age difference between the suitor and the fiancée from the fiancée's family, for the purpose of completing the marriage?

Allah has forbidden lying, and the Prophet, peace and blessings be upon him, threatened liars with Hellfire. A believer must be truthful in their statements. The conditions stipulated for a husband are primarily a right of the woman, and her guardians may sometimes intervene for her benefit, because the Sharia has placed a woman's marriage in the hands of her guardian, as he is more knowledgeable about her interests. Concealing the husband's age is a lie that is often discovered and causes disputes, and the Sharia prohibits whatever causes disputes among believers. The truth must be disclosed, and the choice left to the family, who are then fully informed, along with performing Istikhara; for Allah knows what is best for His servant.