You can add multiple custom fields to JIRA Service Desk customer portal and JIRA issue create/view/edit screens. Each custom field may contain different form assets.
For more information on adding custom fields, please see official Atlassian documentation.
To create a custom field in JIRA please follow these steps:
Configure the selection criteria for the field.
Enter Name for this custom field. For example Computer Assets.
Select the checkboxes of the screens on which this custom field will be displayed.
Custom fields, by default display all the assets of the system. You can limit the forms in Assets configuration page:
Go to Assets > Settings > Custom Fields Configuration
You can filter your custom field by Asset Types or Filter or Reporter's Assets.
If you want to show all assets (default), select Asset Types and leave it empty
If you want to show assets by asset types, click Asset Types and select asset types.
If you want to show assets by a filter, click Filter and select a filter. For Custom Field filters, it can only select from System Filters.
You can filter asset custom contents with Reporter's' Assets
Select "Multiple" to have custom field multiple assets select
Choose or not more configuration options:
Now the custom field will all assets or the assets of the selected asset types or filter or reporter's assets. You can test it at Issue screens.