1. Upgrade Magento to latest stable version (currently ver 22.214.171.124) from ver. 126.96.36.199
2. Update extensions if required to work with 1.5:
3. Allow for importing and updating of simple and grouped products via Magento import tool.
If we need to install an additional extension to get the grouped product import to work that is ok, such as:
4. Ensure theme compatibility with Magento 1.5, especially custom theme templates
Hello, we are ready to provide solution to your Magento site upgrade. Regards