これからカナダに戻り、各手続きをします。
その一つであるChild Supportですが、裁判所のオーダーをとって、今後は支払いの強制手続きをするのですが、今までの未払い分は徴収できるのでしょうか？
ご存知の方いらっしゃいましたら、宜しくお願い致します。

If you're in BC, child support payments can be handled through a government agency called BCFMEP:

http://www.fmep.gov.bc.ca/

"British Columbia Family Maintenance Enforcement Program".

The supporting person makes payments to an BCFMEP account number: BCFMEP actually handles the money, and they deal with late payments, and so on.

About interest:

"We will also charge you daily interest on any late payments, and add it to our records at the end of every month. All interest goes to the recipient."

http://www.fmep.gov.bc.ca/resources/information/information-for-the-payor-who-is-enrolled.php

However, I am not sure whether BCFMEP enforces any outstanding debts which occurred before enrollment in the program. That's a good question for someone from that program.