How to import ICS into S-Planner (Galaxy S7)

How can I import an [ICS file](https://en.wikipedia.org/wiki/ICalendar) into S-Planner on my Galaxy S7 ? An ICS file is an exported calendar from another application. Btw: I know how to use Google calendar and then sync S-Planner with it but I definitely don't want to merge Google calendar with S-Planner calendar. The calendar I want to import into S-Planner is an independent calendar. If S-Planner cannot import an ICS file, an alternative would be to have a Google calendar imported (not sync'ed) into S-Planner. Thanks.