
Correct. Further refresher below:
Tia forced the saintess to marry her brother in her first attempt at life and felt sorry for her. The saintess ended up getting sick and Lawrence resented her since she was loved by the people while he was viewed as a tyrant so he let her wither away in an isolated place with no help. Her last words to Tia were to let Cedric know that she lived and passed on so Tia thinks that Leisha loved Cedric which is why she said that their marriage is temporary. She wants Cedric and the saintess to get together to make up for the sins that she committed against them in the past and to prevent Lawrence from taking the crown but she needs the temporary marriage rn so that Cedric can succeed the dukedom to grow his power (due to the will the previous duke left behind about the marriage condition for choosing his successor)
P.S please feel free to correct me if I'm wrong or if I missed anything

Wanted to correct something! I got this story mixed up with Daisy (Lisabel) at the end of my last comment. The reason for Tia and Cedric's marriage was so the emperor would be less suspicious of Cedric and so Tia could inherit her title and fortune. It is still the temporary marriage (as of now) but it was not because of the duke's will. It will still help Cedric to inherit the Dukedom and eventually gain the power to become king though.
who’s leisha again hsbsjnsk
http://www.mangago.zone/read-manga/the_villainess_lives_twice/uu/ibx_chapter-44/pg-13/