Update multi-value lookup fields from source to destination lists.

Hi Folks,

I would like to share my experience on updating the multi-value lookup field values from source list to multi-value lookup field in destination list.
I tried several things but one thing is sure, we cannot achieve it using SharePoint 2013 workflow 'Update List item' step. I had to include SharePoint 2010 WF within SharePoint 2013 WF. Also, I need to keep current item's lookup field type as 'string' to make it work.

'Update IT Systems' is SharePoint 2010 WF which I started within SharePoint 2013 WF. Please see below.

It resolved my issue. The big part is none of the blogs in google have provided a working solution. So, I am writing this blog to save some lives :-).

Thanks,
Kunal