Is it obligatory to inform the suitor about a previous invalid marriage, especially since the family is unaware of it, taking into consideration that informing him might lead to disbelief or inappropriate classification?

If the marriage was conducted by a Sharia judge who does not consider the guardian (wali) a prerequisite, and it was witnessed by two just witnesses, then the marriage is valid. However, if it was not conducted by a Sharia judge, it is invalid, based on the Prophet's (peace and blessings be upon him) saying: "There is no marriage without a guardian," and "Any woman who marries without the permission of her guardian, her marriage is invalid, invalid, invalid."

In the case of an invalid marriage, it is permissible to marry another man after the waiting period ('iddah) from the first one has ended, and it is advisable to keep the matter private.