I’m wondering how to prove my husband has another bank account. Also wondering if lawyers would recommend him to tell or would they give advice to keep quiet?

We will assume that you are already separated from your husband, and have started divorce proceedings.  At this point, each of you has a legal obligation to provide “financial disclosure” to the other (and to the court), which gives a full and truthful snapshot of your respective financial situations. Your husband’s obligation to make full financial disclosure encompasses a wide assortment of financial information, including his bank accounts and savings (as well as his investments, debts and liabilities, real property holdings, pensions, RRSPs, RRIFs, TFSAs etc.).  Legally, he has a duty to provide this information voluntarily; if he does not, then the court has an array of sanctions that it may impose against him.   By extension, his lawyers would be likewise obliged to facilitate his coming forward with his information – and certainly should not advocate that he “keep quiet”.