The effect is shown by love and affection, tolerance and understanding toward one another. The siblings recognize the wisdom in their mother and take her advice and guidance to heart.
If you are married to your daughter's mother, then her boy is your stepson. If you are not married, then he is no relation to you. Either way, he is your daughter's half brother.
If Tara's daughter is your daughter's mother, and you are a woman, you are Tara's daughter.
Your mother's son is you or your brother. Your mother's son's daughter is your daughter, or your niece. Your mother's son's daughter's mother is your wife, or your sister-in-law.
Your mother's brother is you uncle and your daughter's great uncle. Your daughter is his great niece.
Her aunt
niece
Mother's grandson as regards her daughter is either her (daughter's) son or her (daughter's) nephew.
If Paula's mother's mother had only one daughter, that is the same as saying that Paula's grandmother had only one daughter. Therefore Paula is the daughter of the only one daughter that her grandmother had.
A second cousin.
It would be a second cousin.
The relation of the mother;s sister to daughter is niece-aunts.
Physically it is possible, just as mother and son can have sexual relationship.