Currently the insert rule is registered as 20,000. Then for normal fields, it multiplies the field priority by 10 and adds the rule. Because the zLegacy fields are already automatically added to design with 1000 + the original field most of the 1000 field numbers can already be used on large tables. i.e. 389 - PaymentTerm - 1389 zLegacyPaymentTerm. So most utility fields get added starting in the 2000 range. The problem with that is that when they are registered by Autogen and it multiplies by 10 the rules get registered after the insert rule. i.e. if you start your additional fields at 2000, 2010, 2020, they will get registered as 20100, 20200, etc which is all after the insert rule. If we could move the insert and delete rule to 199999 and 200000, we wouldn't have to worry about this anymore.
We would also have to move any cross reference inserts to after the insert rule so greater than 200,000.
I have ran into this issue as well. It makes sense to create a parameter for these rule types rather than hard code this and find it needs to be modified later.