Here you can see if 2 boxers can meet each other according to Danish Boxing Association DaBU rules.
Excerpt from DaBU’s Competition Rules
See the entire regulation here
Age groups:
If a bout are boxed across age groups, there must be a maximum age difference of 24 months, the 2 boxers in between. This age difference is determined on date of birth. When fighting across age groups (agreed and approved) by coaches and officials), are always boxed on the youngest’s terms. U19 may not meet elite, at championships and international tournaments. nationally is exempted from this rule so that the 24 month rule (on the date) applies. there boxed according to U19 rules, which means that all matches are boxed with a helmet.
Weight classes:
Boxing that crosses weight limits, lowest weight class is crucial for weight difference, they two boxers in between. Ex: A boxer weighs 62. Kg. The weight class is 60 – 64 kg. Boxes must meet opponent there maximum weighs 66 kg.