Someone married a woman whose brother married her husband's sister

Q: I am a young Saudi and I proposed to a girl from my tribe when I was a university student. I paid part of the Mahr (dowry to a bride from the groom) which is 50,000 riyals as agreed upon among the tribe members. However, due to my studies, I could not help but to delay the marriage. During that period my fiancée's brother proposed to my sister and offered 50,000 riyals as Mahr. This happened three years after concluding my marriage contract to his sister. After my graduation, I asked my In-laws to set the wedding date, but they insisted that my wedding and that of their son be held on the same day, bearing in mind that I paid the Mahr in full and so did their son. Is this considered (Part No. 18; Page No. 433) a form of Shighar marriage (exchange of daughters or sisters for marriage with no mandatory gift to a bride from her groom) or is it a valid marriage? I should mention that the marriage contracts do not include any stipulations between the two spouses.

A: If your marriage to the said girl and her brother's marriage to your sister are concluded without any stipulation and there were no pre-agreement that each one of you would marry his sister to the other, then the marriage is valid as long as its pillars and conditions are fulfilled and there are no legal impediments invalidating it. May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.