I have different indexes that contain different fields I need to aggregate all of them, what i mean i have index1 and index2 in index1 I have ch and in index2 I have ch2 how can i add ch to ch2 with script or script field

[ghramalhajyalhajy (غرام الحاجي الحاجي)]

search index
PUT index1/_doc/1
{
"foo": "bar"
}
GET index2/_search
{
"query": {
"match": {
"foo": "bar"
}
}
}