3 sentences

1. 这对母子正在公园里散步。

   zhè duì mǔ​zǐ zhèng​zài gōng​yuán lǐ sàn​bù.

   The mother and son are taking a walk in the park.

   Source: Dong Chinese Dictionary

2. 这两家企业是母子公司的关系。

   zhè liǎng jiā qǐ​yè shì mǔ​zǐ gōng​sī de guān​xi.

   These two enterprises have a parent-subsidiary relationship.

   Source: Dong Chinese Dictionary

3. 这笔欠款必须母子一并清偿，不能拖延。

   zhè bǐ qiàn​kuǎn bì​xū mǔ​zǐ yī​bìng qīng​cháng, bù néng tuō​yán.

   This debt must be settled by both the mother and the son together, and no delay is allowed.

   Source: Dong Chinese Dictionary