Sentence examples similar to grand undertakings from inspiring English sources

"granddaughter undertakings" is not a correct or commonly used phrase in written English
It is unclear what it is intended to mean. If you are trying to refer to something your granddaughter is doing or has done, you could say "my granddaughter's activities" or "my granddaughter's endeavors." If you are trying to refer to something you have undertaken with or for your granddaughter, you could say "our joint projects" or "our shared tasks." Without more context or understanding of what you are trying to convey, it is difficult to provide a specific example.