It would be cruel to tell a loving brother-or sister-that doing something special to honor the bride and groom is absolutely forbidden. So let’s look at the spirit, rather than the letter, of the “no showers from family” rule and see what options might work for you.
The spirit of the rule is that neither family should be hitting up guests for major gifts that the happy couple need to set up housekeeping. Since the purpose of a shower is to “shower the bride (or couple) with gifts,” the family properly does not host showers. There has always, however, been an exception that allows the bride’s sister to host a shower if she is the bride’s maid-of-honor, or to co-host a shower if she’s one of the bridesmaids. A less-known exception is that, if the bride’s circle of friends includes several family members, they may throw a shower amongst themselves.
This rule leaves you four major loopholes big enough to squeeze a party through. First, are you a member of the wedding party? If you are, you may throw a shower in that capacity. Should you happen to be officially the groom’s attendant, rather than the bride’s, don’t let that stop you! If the happy couple is comfortable with a couples’ shower, the groomsmen may certainly host it, either by themselves or in conjunction with the bride’s attendants.
Second, are there friends that you share with the bride, but that are not friends of the bridesmaids? If these friends are invited to the wedding, they can also make up the guest list for your shower. This strategy is a little bit risky, but many families are comfortable with it.
Third, the “no showers from family” rule is meant to prevent family members from soliciting major gifts. There is no problem with holding a theme shower that calls for token gifts instead. There are lots of small touches that homes need, from green plants to candles to matching coffee mugs. If your invitation specifies small gifts, and your shower puts the emphasis on entertaining the guests and having fun, then there is no reason for people to be offended.
Fourth, must you throw a shower? Is it vital that the event include gifts for the bride and groom? So often, people involved in a wedding proceed under the assumption that the only possible pre-wedding events are the engagement party, showers, bachelor and bachelorette parties, and rehearsal dinner. In fact, it is perfectly proper for any well-wisher to hold a party in honor of the happy couple, at any time during the engagement. The party is simply a gathering to entertain friends and does not involve gifts. You do, of course, also have the option of volunteering to host the rehearsal dinner or another typical pre-wedding event.