All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
The Prophet said: “What is made unlawful by reason of blood is made unlawful by reason of the relations based on suckling.” [Al-Bukhari and Muslim]
Here are some conditions:
1) According to the preponderant opinion among Muslim scholars, one must suckle five times at least.
2) According to the majority of Muslim scholars, suckling for five times must be during the first two years of the child.
Thus, you are allowed to marry your cousin (Khala's daughter) since she suckled only once.
Here, we say that there is no difference between our Fatwa and Ibn Baaz's Fatwa.
Finally, you have to know that one suckling means that 'a child takes a woman's breast and then leaves it by him/herself. In addition, the child may suckle such five times one after the other in one sitting.’
Allah knows best.