Complex sentence: On 6 April 1663 was finally announced the betrothal between Margaret and Leopold I; in the marriage contract signed on 18 December, besides the customary dowry, was particularly included, as a gift from her father, the famous Wittelsbach-Graff Diamond.
Split into simpler sentences: On 6 April 1663, the betrothal between Margaret and Leopold I was finally announced. In the marriage contract signed on 18 December, besides the customary dowry, was particularly included, as a gift from her father, the famous Wittelsbach-Graff Diamond.