After reading the EULA again myself, I'm' a bit confused where it says it restricts a family to one license of Pro (unless you all want to use different computers). Your copy of pro is for the installation of one computer. However, if another person in the house wants to use Unity, they can use Indie on there own computer. They should supply there own email address to register with free.
Just realize that these projects/creations cannot be used with both versions of Unity, so you'll have to make your own games if your using Pro, and they will have to make their own indie games. If you don't necessarily need the Pro features for creating a game, you could always stick with using Indie until your budget allows for the purchase of multiple copies of Pro.
Unity3D isn't restricting families from using Unity. Realistically, Unity is a tool made for game developers (which many are a part of a company or have there own) to develop games and sell them, this is how UT earns money. Your purchase of Unity3D pro is not for multiple people, it's a SINGLE user license from what i have read.
Here is a snippet of the EULA:
1) GRANT OF LICENSE:
Subject to the terms below (the
'Agreement'), Unity Technologies A/S
hereby grants you a non-exclusive,
non-transferable license to install
and to use Unity or Unity Pro or Unity
Educational (the 'Software').
Except during the trial period, the
Software must not be used without a
valid license. A license of the
Software must only be used on one
computer at a time. The Software may
be installed on a second computer for
sole use by the user of the License
except for discounted Academic
versions which may only be installed
on a single computer. You may copy the
Software for back-up or archival
purposes. For the avoidance of doubt
the Software is licensed on a per-user
basis and a computer means a
combination of hardware and single
operating system.
You agree to terminate your use of the
Software on the date agreed if you
have purchased a term-based license.
The standalone runtime may be
redistributed royalty free, as long as
it is produced using a licensed
installation of the Software.
Copyright notices from Unity
Technologies A/S and NVIDIA
Corporation may not be removed from
the standalone runtime. The Unity Web
Plugin may only be distributed by
Unity Technologies A/S.
2) LICENSING RESTRICTIONS:
(a) Unity Pro may be licensed by any
company, educational institution,
incorporated entity, or individual.
(b) Unity (free version) may not be
licensed and used by companies,
educational institution or
incorporated entities that had a
turnover in excess of US$100,000 in
their last fiscal year.
(c) Discounted academic versions of
Unity or Unity Pro may only be
licensed by educational institutions
for use by their students and staff.
The license is granted for learning
purposes and may not be used for
publishing commercial content.
(d) A company, educational
institution, incorporated entity, or
individual may not license both Unity
Pro and Unity at the same time.