nb-select multiple not loading data

### Issue type

**I'm submitting a ...** (check one with "x")

* [ ] bug report
* [x ] feature request
* [ ] question about the decisions made in the repository

### Issue description

**Current behavior:**
I need to use nb-select multiplely but it gives me an error loading the data:
**Error: Can't assign single value if select is marked as multiple**

**Expected behavior:**
The nb-select multiple works perfect when saving the records but does not allow loading when editing the record, another doubt is that I want to save the services as an object and not as an arrangement as nb-select currently does

**Steps to reproduce:**
Below is nb-select code:

{{ clinica.nombre }}