Allocation of monthly payment to annual purchases

Hi hive mind

hoping you can help me a simple explanation on this one, MYOB online chat didnt understand what I was trying to do.  Apparently someone is going to call me back in a week, hoping someone here can help 

Note:  I'm not an accountant or bookkeeper, just a basic (and very frusrated) user who really struggles with Accountright

Anyway, here is my issue.  I have multiple annual purchases from one supplier (it's insurance if that matters)

I have created a Purchase for say $1200 for business insurance, and bank payments are made at $100/month

I have created a second Purchase for say $600 for vehicle insurance and bank payments are made at $50/month

Now I can see $50 and $100 withdrawals in my bank feeds.  These can be identified by the $ amount, and each Purchase has a unique identifier (say ABC for the $50, and XYZ for the $100)

Is there any way I can set these up to be automagically allocated to the correct purchase, or am I destined to contiunue to have to fish them out each month (as per current), refer a post it note as to which one is which, and manually allocate these

Step by step instructions would be appreciated, my skills in MYOB are very low

Thanks in advance