How to connect in mapping from target to any other transformation in Informatica ?

It is not possible to keep transformation after target.. We need to create two mappings. In second mapping we need to take those two targets as sources for second mapping..

I think your question is how to merge the records from two targets after they got loaded? If this is your question then first import the two target tables as source tables. Complete the mapping to load the two targets. In the same mapping drag the two sources and connect to union transformation as you required. In the Menu bar click Mapping -> Target Load Plan... In the Target Load Group Order dialog box select the one to load the targets first.

I think this answers your question.

Make two flows in the same mapping:
flow 1: load both the targets
flow 2: use both the targets as the source and use SQL override to join the tables. Then load them into a single table