We would recommend to wait several weeks to move the day lily after Snapshot application. Please be cautious because the flowers will be stressed from transplanting.
Please refer to the Snapshot product label for a full list of tolerable plants. If you need anything else, please let us know.
I would recommend calling the Cooperative Extension in your area and speak to the master gardener to get the plant identified. I would definitely be happy to recommend something for you when you have the weed identified.
http://www.csrees.usda.gov/Extension/