Hello CharlesLdy,
Because I used arrays in my project, I thought about using nested objects with a script.
However, it seems that nested objects are not well supported by Kibana so I change my conception.
So now if I have an "Array1" type in my index "index1", each entry of my "Array1" would be each entry of my array (input data).
Anyway, I found that you can update an Elasticsearch data in Logstash using his "_id" (that you can customize if you want to retrieve some data !). Be careful about using a unique "_id" per data.
So, you can imagine to have an "Array1" type in your index "index1" with three columns "C1", "C2" and "C3".
First, you put your new data (with an id that you build an can retrieve easily), then you can use the "update" function using the id that you build to update your array if some new data are coming in.
Well, if you can change the format of your data, it could be a great idea to send all your data once 
Ask me for few questions if i'm not clear