Separation of weddings

1) To implement the Laws of Hijaab.

2) Yes. There are numerous Qur'aanic Ayats and Ahaadith on the Laws of Hijaab. Here is an example:

Rasulullaah  also said, Looking (at non-Mahram men and women) is the fornication of the eyes, hearing (them speaking) is the fornication of the ears, speaking (to them) is the fornication of the tongue and touching (them) is the fornication of the hands, walking (towards them) is the fornication of the feet, desiring (them) is the fornication of the heart and the private part either culminates the act (of fornication) or shuns it.[1]

[1] Muslim (Vol.2 Pg.336) and Abu Dawood (Vol.1 Pg.299).

Will be forwarding book on the Laws of Hijaab in detail for further understanding.