Contacted through email, stating both FFP numbers and attached a photo of Enrich card and monthly statements for a year. Received the following reply after 3-4 days.
"Thank you for choosing to become a member of Oman Air’s Sindbad Program.
We are pleased to inform you that your tier has been matched as per you’re Malaysia Airlines membership account.
If you have any further queries or concerns regarding your Sindbad membership, please feel free to email us."