Does the wife have the right, according to Sharia, to object to her daughter being breastfed by the husband's sister, so that the latter becomes her daughter by suckling?

If there is no harm to the girl or to you from her suckling from her paternal aunt, then it appears that you do not have the right to object to your husband’s wish for that, so that the aunt becomes a foster mother to the girl. Understanding and cooperation are necessary in such matters.