MongoDB: How to merge original record back after lookup - mongodb

Question

I have the following collections which I am using a $lookup to bring together:
{
"organizations": [
{
"_id": 1,
"name": "foo",
"users": [1,2]
},
{
"_id": 2,
"name": "bar",
"users": [1]
}
],
"users": [
{
"_id": 1,
"name": "john1 smith"
},
{
"_id": 2,
"name": "bob johnson"
}
]
}
The query works fine:
[{
"$lookup": {
"from": "users",
"localField": "users",
"foreignField": "_id",
"as": "members"
}
},
{
"$unwind": "$members"
},
{
"$group": {
"_id": "$_id",
"original": { "$first": "$$ROOT" },
"members": {
"$push": "$members"
}
}
}
]
however, the resulting organizations records don't return all of their properties without adding the original prop which gives me back a nesting of the original organization:
{
"_id": 1,
"original": {
"_id": 1,
"name": "foo",
"users": [
1,
2
],
"members": {
"_id": 1,
"name": "john1 smith"
}
},
"members": [
{
"_id": 1,
"name": "john1 smith"
},
{
"_id": 2,
"name": "bob johnson"
}
]
}
I'm trying to get everything in the original prop back into the root along with the new members array.