I'm Baptist, and Lent is not something Baptist take part in. At the same time, I have to give dredit to Lent. A few years ago my wife (formter catholic) asked me what I would give up for Lent. At the time I doubt anyone would call me a christian, but I told her that for Lent I would read 400 pages of the bible over Lent. That made her happy.
Of course, looking back on it, my wifes' Catholic parents are not too happy with that decision. Now my entire family is Baptist. While committing to read the Bible over Lent did not result in my immediate turning Christ, it definately played a part....
As a Catholic parent, I can honestly say I would rather have my children be fervent Christian Baptists, than lukewarm Christian Catholics. (Not that I wouldn't be praying for their reversion, mind you).
I'm sure there are many Catholic folks on these boards who disagree with that sentiment, and I suppose your in laws do too, but really nothing breaks my heart more than a cradle Catholic who has completely fallen away from Christ. I would be greatly comforted by a child's faith in Our Lord.