More than one period with a repeat interval should be configurable

Current Situation

A schedule element e.g. day can have multiple periods with a repeat interval or single starts.

    <weekdays >
        <day  day="1 2 3 4 5">
            <period  repeat="01:00" begin="00:00" end="12:00"/>
            <period  repeat="00:30" begin="12:00" end="24:00"/>
        </day>
    </weekdays>

If the schedule element has already a period with a repeat interval and a new period will be added then the new period doesn't have the option to select a repeat interval in JOE.

Desired Behavior

It should be possible whenever a new period will be added that all options (single_start, start/start interval and start/end interval) are configurable.