A question about dstiributive singular/plural

[Snappy]

If I want to say that a fixed gross margin rate is necessary to a group of spare parts, another fixed gross margin rate to a different group of spare parts, etc. Is it okay to say like this?

"The introduction of a fixed gross margin rate is necessary to each group of spare parts."

I'm afraid that the above might mean that a single gross marging rate is applied to all the groups.
I want to say that all the groups are different in gross margin rate.

[Hedwig]

If I want to say that a fixed gross margin rate is necessary to a group of spare parts, another fixed gross margin rate to a different group of spare parts, etc. Is it okay to say like this?

"The introduction of a fixed gross margin rate is necessary to each group of spare parts."

I'm afraid that the above might mean that a single gross marging rate is applied to all the groups.
I want to say that all the groups are different in gross margin rate.

How about something like this?

Each group of spare parts must/should show its fixed gross margin rate.
or
The fixed gross margin rate must be shown beside each group of spare parts.

- Not a teacher -