This might not be possible out of the box with Trello, however, have you tried copying the multi-item list and pasting it in the first item in a checklist on an existing card?
It should split out the multiple items into their own checklist items. This might be a half-way solution for what you're looking for.
So you’re using Trello at work, at home and to track your new DIY crafts. The family and co-workers are all on board and everything is organized, color coded and has a due date. But still, there’s so...
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