How to create one record with two due dates displayed on calendar?

[MIKHAIL LIBERMAN]

I have a project to be executed on a certain day - this is my due day field, it is displayed on calendar.  I have a preparation process, so I have due day for the next step in preparation.  I can add custom field of the Date type, but it is not displayed on the calendar. 

How to get the second date on the calendar?

Thank you! 

[Iain Dooley]

@MIKHAIL LIBERMAN the only things that will show up in the calendar are due dates attached to cards. If you want several items in the calendar leading up to a single delivery date, then you could create those as separate cards, each with their own due date.

You can use Butler to automatically link to those cards from a checklist on the master like this:

When a card is moved to "Create subtasks" convert checklist "Subtasks" into linked cards in list "{triggercardname} tasks"

You can then set due dates on individual cards, and a due date on the master.

You can check items off from the master each time one of the subtasks is archived with another Butler command:

When a card is archived find the first card linked in the attachments and check item "{triggercardlink}"

I wrote an article recently describing how to achieve something similar in Trellinator:

https://community.atlassian.com/t5/Trello-articles/Trello-Subtasks-with-Trellinator/ba-p/1020531