FTS index stop Lists

Is there any way to modify/override stop_en stop list without writing a custom tokenizer?
Motivation: I need to preserve token On in the index. In my database On turned out a first name of Chinese heritage.
Currently indexing as:
“FirstGivenName”: { “dynamic”: false,
“enabled”: true,
“fields”: [
{
“include_term_vectors”: true,
“index”: true,
“store”: true,
“type”: “text”
}]}

Ended up with a custom analyzer without any stop list :slightly_frowning_face: applying it to names related fields only.

@skaryshev a custom analyzer is the correct approach here. stop_en is a fixed list of stop words based on the english language.