Older sister Olivia graduated from OSU in May. Vivian just graduated as she posted her graduation photos on August 22 on her twitter account. While both have one year of eligibility remaining, doesn't look like Olivia has intentions of continuing her hoops career (nothing on her twitter account indicating otherwise). Of course, if a school offers both sisters a hoops scholarship for one year, I can see that being enticing to Olivia moreso for free graduate school for one year and a role player on the hoops squad.
As for intra-conference grad transfers, both would need a waiver from OSU to transfer to another Big 12 conference school. When Erin DeGrate grad-transferred from Texas Tech to Baylor for the 2019-20 season, she had to obtain one from Tech, and it wasn't easy according to Baylor fans. I can see OSU not granting the waiver simply to prevent 2-3 of their players from ending up at fellow conference schools and have to play against them twice a season.
As for intra-conference grad transfers, both would need a waiver from OSU to transfer to another Big 12 conference school. When Erin DeGrate grad-transferred from Texas Tech to Baylor for the 2019-20 season, she had to obtain one from Tech, and it wasn't easy according to Baylor fans. I can see OSU not granting the waiver simply to prevent 2-3 of their players from ending up at fellow conference schools and have to play against them twice a season.