How can we run logstash conf files in sequence?

Elastic Stack Logstash
1

I have following scenario.

I have 4 different logstash files and 4 different document_type.

Conf files         Document Type     CSV file used to get input
  1. doc1.conf doc1 doc1.csv
  2. doc2.conf doc2 doc1.csv
  3. doc3.conf doc3 doc3.csv
  4. doc4.conf doc4 doc4.csv

first two logstash files are using same csv files to get input. In doc2.conf file, elasticsearch filter plugin is used to get particular field data from previous events from "doc1" document type. In addtion , In doc3.conf and doc4.conf, elasticsearch filter plugin is used to get particular field data from previous events from "doc2" document type.

Now I want to run logstash conf files in sequence doc1.conf ,doc2.conf ,doc3.conf ,doc4.conf . I want to implement real time logging. So after running all files how can I ensure sequence ??