Glasspool and Heliovaara pulled off an upset in the round of 16 when the beat the eighth seeded team of Nick Kyrgios and Thanasi Kokkinakis.
Kyrgios and Kokkinakis, seeded eighth in the Grand Slam, were up against Andre Goransson and Yoshihito Nishioka in the second round.
Fognini/Bolelli and Glasspool/Heliövaara will take on each other on Friday July 29 in the finals of the 2022 Croatia open.
Venus and Putz beat the all-German pair of Daniel Altmaier and Jan-Lennard Struff in the quarter-final by a score of 6-3, 6-3 on Thursday.