Hi,
Did you use Smartlist Builder to create these smartlist object or did you use SQL to create SQl views and then added them in Smartlist builder?
If you created this with just out-of-the-ox Smartlist, it should be usable for all companies regardless which company you created it.
If you used Smartlist Builder, you need to turn on MultiCompany access to the object. Refer to the link below regarding this (page 42):