Dear Shreeswamisamrath,
You may write a separate letter to each employee, however, what you need is a comprehensive "Asset Allocation Policy". Under the provisions of this policy, you need to design the "Asset Allocation Form". You need to obtain the signature of the employee while allocating the assets. You need to renew the allocation after every quarter or half-year.
I have given the points on which to design the "Asset Allocation Policy". Click the following link to refer to the said post:
https://www.citehr.com/336602-policy...ny-assets.html
Thanks,
Dinesh Divekar