Okay, so I have to backtrack. I had gotten my actresses mixed up I believe. I don't know if Sadie's parents truly had any objection to the kiss, but what I have now recall (or have been reminded) is that Sadie herself had a bit of an issue with the kiss because it was introduced at the last minute and it was to be her first onscreen smooch. And I can't find fault with that. Actresses far older than her at that time wit far more experience have been known to get a little rattled when male directors introduce nude scenes or love scenes in a script that were not previously there. So I can imagine what a kid like Sadie must have been going through when she was suddenly told she would have to kiss a boy, especially considering she was known to be very shy at that time, much moreso tan her co-stars. She was likely nervous as fuck.
What I did get right is how extremely close she is with her co-star who plays Lucas and how she is such a vocal champion of the relationship between their characters. She has gone on record recently saying she considered the moments with him to be the most special scenes for her character (which is saying a lot considering how they don't share enough screen time imo). Also a short while ago when two interviewers asked her if she favors a romantic pairing relationship between Max and Lucas or between Max and Eleven (because people are obligated to conjure up imaginary gay pairings that don't exist onscreen), Sadie was having none of that nonsense and quickly went with Lucas and Max.
Also I like this quote from her as well"
https://twitter.com/strangerlara/status/1531738270400450561