L1 Visa L2 Question

I have been on an L1 visa for 5 years and family on L2. Ours is due for renewal next month and I would like to know if my family is required to cross the US/CAD border with me at initial renewal (I intend to go) or if they can wait a few months as we have a trip back to Canada already planned in summer. We will have all the documents this week and I plan to go next week but would like to know if they also need to attend initial renewal crossing or if they can do so later?

You mean to your L1 Stamp is expiring and you intend to get new stamp ? In general, as long as you maintain status in US, you do not need new stamp, unless you plan to travel out and re-enter US. Read US Visa vs Status Difference

If you are just getting new L1 stamp for general convenience, then there is no need to have your family along with you for stamping, you can go by yourself and have them do it later…