TiDB-6.5.7 Merge synchronization scenarios

tidb版本：6.5.7
mysql版本：5.7
问题：
目前是通过dm同步mysql数据到tidb集群。现在有个需求。需要把2个不同实例的mysql库的2个表的部分字段合并同步到tidb的1个表里。比如mysql的a.t1有(a,b,c,d)4个字段，mysql的b.t1有（a,d,e）3个字段。现在要合并同步到tidb.t1(a,b,d,e)这4个字段。其中a是主键。请问dm支持这样的场景吗？如果支持，请给个配置例子。谢谢！

Start with the issue's described DM synchronization scenario and check the DM documentation and configuration guidance for merging tables from separate MySQL instances into one TiDB table. Confirm whether this topology is supported, identify any documented configuration example, and record the limitation or example as the completed outcome.

Written by the indexing model from the issue text.