Hi, substitutions are kept in WFCovers.
here is my statement to show them in SQL grid.
SELECT TOP (100000) convert(varchar,[COV_CoverStart],104) as begin
,convert(varchar,[COV_CoverEnd],104) as end
,Person = (select COS_AD_displayname from [CacheOrganizationStructure] where COV_person = COS_AD_userprincipalname),
Substitute = (select COS_AD_displayname from [CacheOrganizationStructure] where COV_Cover = COS_AD_userprincipalname)
FROM WFCovers covers where convert(date,COV_CoverEnd,104) >= convert(date,getDate(),104) and cov_isactive = 1