Multiple workbooks need to be connected and update together

I'm getting frustrated because this seems like it should be easy.

I have 11 individual users who update the same workbook with 5 columns but if more than one of them are in it, which happens often, the wb gets locked.

I thought I could give them each their own workbook, keep one as a master and have their individual wbs update the master and the master update their individual wbs. Does that make sense?

Column a is Customer Name, col b is Customer Number, col c is Date Received, col d is Analyst Name, col e is Date Taken. Column a, b, c are all input on the master workbook. Col d and e are input by whichever user accepts the case.

If user Ann, has her wb open and takes the case on row 10, I need user Charlie to NOT take it too, so he has to see her column d and e. When a new case is entered on master row 15, I need both Ann and Charlie to see it.

Does anyone have any ideas? And please, another application, like Access is NOT an option,

It isn't 'supposed' to get locked when multiple users are in it but it still happens. And giving each employee their own worksheet would be fine if they were all using different information but it would be the same on every worksheet, the first row on one would match the first row on all, the second would match the second on all, etc.

So if the first sheet is the main one, the second is for Ken, the third for Barbie, the fourth for Skipper, etc, when Skipper takes the case on the second line and updates her ws, that entry has to show up for Ken and Barbie, too, so they don't take the same work. How would the other ws know what she'd put in? Unless each possible cell had IFs set up that looked for data in the corresponding cell but on every ws. Very long since there could be up to 11 other ws in one workbook.