Afro are you okay?
The fact that her other sibling is speaking out telling the tabloids how their sister isn't doing shit should be enough to let you know that this is a GRUDGE. Her sister, Allison has spoke about this her damn self.
grudge
ɡrəj/
noun
1.
a persistent feeling of ill will or resentment resulting from a past insult or injury.
"she held a grudge against her former boss"
synonyms: grievance, resentment, bitterness, rancor, pique, umbrage, dissatisfaction, disgruntlement, bad feelings, hard feelings, ill feelings, ill will, animosity, antipathy, antagonism, enmity, animus; informala chip on one's shoulder
"a former employee with a grudge"
verb
1.
be resentfully unwilling to give, grant, or allow (something).
and since when is silence indication of indifference?

It's indication of unwillingness. Again, Mariah has the ability to shut this all down but she isn't because she's holding onto a grudge. Period.