You can’t call a function with parameters from the template. You can only do this in the view. Alternatively you could write a custom template filter, which might look like this:
@register.filter
def related_deltas(obj, epk):
return obj.get_related_deltas(epk)
So now you can do this in the template:
{% for i in channel_status_list %}
{{ i|related_deltas:3 }}
{% endfor %}