how do I create an excel spreadsheet for scheduling thousands of links across a hundred different reddits over months

Column1 is for the links I'll be posting. Column2 is the name of the subreddit it will be posting to. I've got over 80 different subreddits and hundreds of different links. So, for example for one subreddit, I've got 30 column2 cells filled with "r/yummypawgs" and next to each of those in column1 is a link. I've got all my links filled out for all my subreddits. It fills up 7000 rows. Column 3 is the post at date. Some subreddits, I want to have them post every 8 hours, other subreddits, they need to post every 24 hours. Certain subreddits MUST have their links posted before any of the other ones. Column 4 is the title going with the link--which I don't have filled out yet. IDEALLY, for each individual subreddit, no title will be repeated as the days go on. Moreover, IDEALLY, per day, there will be no more than 2 repeating links across all the subreddits I post to. FINALLY, all this information needs to be transferred and formatted for a template I upload to my scheduling site. That template basically has the same subheadings: title, post at, link, subreddit. I want to be able to easily ADD new links to each subreddit--so I need dynamic ranges or whatever. Like, I want to be able to add the same 15 links to 20 subreddits at a time, but I want to add those links to the top of each subreddit/link list so that they'll post next, and I want to randomize those links when they are added to each subreddit so that each subreddit isn't posting the 15 links in the same order.