Re: Obligatory Prayers : 3 or 5 ?
When I've asked Shia relatives about it, they mention that the Prophet used, but they definitely also point out that the Quran only mentions three prayer times and combining prayers brings their practice more in line with that...
Peace janab-e-ali
Then perhaps your family may have forgotten about Surah 20 Verse 130 ???
To me it is clear that the Qur'an mentions all of the prayer times. However, to those who say the Qur'an ONLY mentions 3 prayer times. It does not mean at any point that the Qur'an ONLY legislates those 3 prayer times and no more. For that to be true you will need to provide a verse that does more than just mention prayer times but instead say ... such and such has been prescribed for you for such and such times no more no less etc.
However, please read 20:130 to satisfy your concerns.