Need advice adoption another kitten when i already have one

So, i adopted a 2 months old kitten on 4th July now he is 4 months old (Indie Cat)

Yesterday i found out her sister still not got adopted now I am thinking to adopt her too (and yeah you guys were right always adopt in pairs)

Just wanted to know if i adopted her will they know they are family (brother and sister) or as couple??

(Picture of him then his family)

He also have a brother but person said he can take care of them so its fine