The shrine of Sakina is in Dariyya near Damascus. It has been reconstructed recently by Allama Sayyed Ahmad al-Wahedi  who has compiled number of narrations supporting that Sakina was a daughter of Imam Ali (AS) and Fatima (AS) including:

1. A narration in Mustadrak Safeenatul Bihar by al-Namazi, vol.5 , p.90 in which imam Zainul Abideen (AS) narrated from Sakina about the greatness of Fatimah (AS).

2. In Amaali al-Tousi a narration from Imam Husain (AS) mentioning Sakina his my sister (Wasa'il al-Shia by al-Hurr al-'Aamili , v. 14, p.168).

3. In Biharul Anwaar (v.45, p.104), a narration that Ameerul Mo'mineen (AS) called all his children by their names to say fair well to their mother Fatimah (AS) before her burial and mentioned Sakina among them. 
Wassalam.