Do my parents have the power to make me do whatever they want?
What does Torah say about grandparents offering parents a suggestion regarding Chinuch of their grandchild?
What if parents say they are not interested in hearing any suggestions?
Does Torah address the tone of voice parents use in response to their parents offering a suggestion?
There is nothing wrong with grandparents offering a suggestion and one should not be disrespectful and openly deny even listing to a suggestion.
If however they ask them to follow their suggestion, when it is not their business and doesn’t affect their life, there is room to be lenient as not to follow in certain circumstances, but of course in the most honorable manner. However, each circumstance should be preferably discussed with a Rov to decide whether in that case one may not follow their parents.
See more about this in Halacha2go.com article #529
שו”ע יוד סי’ ר”מ ס”ב, שם סכ”ה ברמ”א. וכבפנים כ״ד אדה״ז באג״ק סמ״ו (במהדו״ח).
דנו בכמה שו”ת בנושא זה ראה לדוגמא שבה״ל ח”י סי’ קנ”ו. בצל הכחמה ח”ב סי נ”ה. וראה כנסת ישראל סי ל”ה וחוות יאיר סי רי”ד ועוד כו”כ.
וראה בארוכה בעיונים להלכה יומית הנ״ל.