1.发现婚姻中的一方有“小三儿”后,可在第一时间内让过错方写下“保证书”“悔过书”或“道歉书”等书面资料。保存好这些资料,发生诉讼可作为有利证据使用。2.搜集一些证人证言。向“小三儿”居住地的邻居、物业或居委会及附近的居民了解情况,争取取得一些书面说明或证明,必要时候,可以请求执法部门介入,帮忙调查取证。 1. After finding out that one of the parties in the marriage has the “three children”, he can write down the written information such as “warrant ” “repentance ” or “apology ” within the first time. The preservation of these materials, litigation can be used as favorable evidence. 2. Collect some witness testimony. Learn from the neighbors, properties, neighborhoods or residents in the neighborhood where you live, and obtain some written explanations or certificates. If necessary, you can ask the law enforcement departments to intervene to help investigate and collect evidence.