Hi Gopher, the only other suggestion I can make is ivy, which may stand a chance of competing with your ground elder, it to can be varigated in many colours though maybe if your hollies are varigated you would be better to go for our native green variety, apart from that, I think I'm stumped - ground elder is such a pain. Ivy is a good wild life plant providing winter cover for insects, though not the most beautiful plant I have to admit. I think Thunderbirds symphytum (comfrey) could work and is probably worth a try, (beloved by bees) beware though it spreads almost as much as ground elder H.