Answer
Wa `alaykum As-Salamu waRahmatullahi wa Barakatuh.
In the Name of Allah, Most Gracious, Most Merciful.
All praise and thanks are due to Allah, and peace and blessings be upon His Messenger.
Dear questioner, we would like to thank you for the great confidence you place in us, and we implore Allah Almighty to help us serve His cause and render our work for His Sake.
Answering your question, Sheikh Ahmad Kutty, a Senior Lecturer and an Islamic Scholar at the Islamic Institute of Toronto, Ontario, Canada, states:
Cremation is not an Islamic practice. So, a Muslim cannot perform the rituals associated with that. However, Islam does not impose its particular religious laws on those who practice other religions. Non-Muslims living under Muslim rule have been practicing their religious rituals, without any interference from Muslims.
Therefore, even though you are not supposed to perform such rituals, you are allowed to attend the non-Muslims who practice cremation.
Allah Almighty knows best.