Vinelab/NeoEloquent - Realtionship to a exisiting node - neo4j

Question

I am using Vinelab\NeoEloquent for a new project for Neo4j. I have a registration where people can supply interests (as nodes). When registering, first the user is created, then the interests are created (if they don't exist), an given a relationship of "Interested_In" from the person to the interest nodes.
Problem I am having is when the interest already exists (unique by name property) and I just want to create a relationship from the person created and the Interest node.
In my People Model I have (Since 1 person can have many interests):
public function interest(){
return $this->hasMany('App\Models\Interest','Interested_In');
}
In my create user function in my repository I have a section where it searches the Interests and returns one if one exists. Problem is I don't know how to then create the realtionship from People to Interest. I try to save it as
$interests = explode(',',$input['tags']);
$int = new NeoInterestRepository();
foreach($interests as $interest){
$existing = $int->find($interest);
if(count($existing)){
$person->interest()->save($existing);
}else{
$my_interest = $int->create($interest);
$person->interest()->save($my_interest);
}
}
But I get 'Argument 1 passed to Vinelab\NeoEloquent\Eloquent\Relations\HasOneOrMany::save() must be an instance of Illuminate\Database\Eloquent\Model, instance of Illuminate\Database\Eloquent\Collection given'
I see the associate() function but its only for BelongsTo which doesn't seem to apply.
Any ideas?