What is bootstrap multiselect?
Bootstrap Multiselect is a jQuery based plugin that allows users to tick multiple options from a standard Bootstrap select. Its implementation is quite simple, and in exchange brings a lot of UX value. Examples of Bootstrap Multiselect use: Ingredient choice within a pizza delivery system.
How do I select multiple options in a dropdown in bootstrap?
You can use select data-mdb-container option to resolve this problem. The data-mdb-container accepts selector of the element inside of wich select dropdown will be rendered.