Montrezl posted to his Instagram story, saying: "Don't worry Ma Ma your grandson on the way."
Harrell was with the team for the NBA's restart in Orlando, Florida. He is expected to rejoin the team again, as first reported by The Athletic.
Coach Doc Rivers on Saturday morning said he isn't sure when Harrell will return but that the Clippers will wait as long as needed. Scrimmage play begins next week and games are scheduled at the end of July
"Things happen in our lives, so we've just got to leave it there," Rivers said Saturday. "It's obviously a personal matter at home that he did need to go to. So we're just going to wait for him. Like when he needs to get back, he'll be back."
The Clippers were already shorthanded before Harrell's departure. The team closed its facility prior to traveling to Orlando after a member of its travel party tested positive for the coronavirus, ESPN's Adrian Wojnarowski reported on July 2.
When asked about the status of Marcus Morris Sr., Ivica Zubac and Landry Shamet on Thursday, Rivers said he didn't know. The Clippers had just gotten JaMychal Green out of quarantine on campus after the power forward arrived to Orlando earlier this week.
"To be honest, JaMychal walked in and surprised the hell out of me," Rivers said Friday. "Because they're in quarantine and stuff, you don't ever know."
Before practice on Friday morning, Rivers would not say whether the Clippers had gotten any new arrivals to the NBA campus at the Walt Disney World resort.
"As far as guys that have showed up and not showed up, we don't talk about that," Rivers said. "So we're going to continue to not talk about it."