Hi, Claire! I think you've guessed pretty well. I should think they are all Yiddish variants of TOVA. All I could find besides is the given name Täubchen (with A Umlaut after the T), which means "little dove" im German and was used in the 18th century. In Seibicke's HDV I also found a reference for TOYBE (the Yiddish pronunciation of "Taube", dove), but it was not clear, whether this really was a name. It could well be that the two meanings mingeled.