I have a separate named calendar in Outlook originated 20 years ago for a realtor to show client closing date, birthdays, kids birthdays, and wedding anniversaries and color coded by category. There are multiple entries (max is 8) on a given date. Outlook has now merged it with the basic calendar used for appointments, and removed the color coding. I have exported all the events into an Excel file.
Can Libre Office give me a calendar just for these events every year with color coding?
It will not give… YOU may be the one, who is able to program/design a calender like table. Color codes are possible.
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Years ago I modified a public calendar template for memorial dates/public holidays and you may find several threads where people ask for help with such problems…
A spreadsheet is not the best tool to create a calendar. If you feel adventurous, you could have a look at programs specialised in the calendar domain, notably genealogical applications. Among others, GRAMPS, which is free, can generate a clickable web calendar (you display it with a web browser; no need to configure a server, you can access directly the files with your web browser and it follows the file links). You just need to map your events to Gramps concepts: persons (= client, kids, …), families (for weddings), events (=birth dates, death dates, wedding dates, …). It is then really easy to add or remove persons and events.