Merging Plans on two different vesting schedules

[Alex Daisy]

Company A (surviving plan) acquires Company B and the plans will be merged effective 1/1/2017. For the company match, Company A (surviving plan) has a 1-5 year graded vesting schedule and Company B has a 4 year graded schedule.

Can Company B increase the existing matching vesting schedule to 100% vesting for existing participants and then be on the same vesting schedule as Company B for any new matching contributions effective 1/1/2017?

Or does the merged plan need to keep the Company B employees who were eligible before 1/1/2017 on the more favorable 4 year graded vesting schedule?

[Alex Daisy]

Correction: Can Company B increase the existing matching vesting schedule to 100% for existing participants and then be on the same vesting schedule as Company A (surviving plan) for any new matching contributions effective 1/1/2017?