AEM 6.5.8 Search suggestion - how extend and 0 result

Hi community,

i'm working on a client new website.

the existing website in also on AEM 6.5 and the new it's a version with new feature.

current site is mapped on:

/content/currentSite/*

and the new on:

/content/newSite/*

I have the question about the suggestion query:

1) in the new site, i need to index also to extend the suggestion on jcr:description.

How can i extend the index in order to achive the result?

Can I extend the existing /oak:index/cqPageLucene/indexRules/cq:Page/properties introducing the new node like:

{
"jcr:primaryType":"nt:unstructured",
"nodeScopeIndex":true,
"useInSuggest":true,
"propertyIndex":true,
"useInSpellcheck":true,
"name":"jcr:content/jcr:description",
"type":"String"
}

?

Is it a best practice extend existing index? in case of yes, how can i deploy it (including in the solution the index override or installing through package manager)

2) My localhost suggest results are different than the client's environment. Using for example the <brand> word, the client environment has returned 0 results but my localhost 10 result.

Log file are not report warning message.

Investigating, I discovered that IF i installing also the currentSite content on in my localhost environment, i'm getting the same result of client environment.

Below the index status before and after the currentSite content.

If i delete (in incremental mode .. 20%; 40%; 60%; 80%; 100%) the currentSite content, in progress mode (after the reindex) i get one or more results.

Have some idea about? why this behaviour? is it documented in order to understand the reason and discussing it with the client?

thanks in advanced!