You will need small vials for each participant, and a large vial for the final product. Bridal shops can provide vials and sand, and they usually have a wide variety at reasonable cost. Parents' vials should be larger than the children's. The idea is for each participant to start with enough sand in their container to exactly fill the final vial when completed. To calculate the amount of sand needed in each container, I recommend this procedure:
First, fill the final vial with water, right to the top, leaving only enough space for the stopper.
Pour water from this vial into each of the children's vials, then the balance, equally into the parents' vials. If there is not enough water to go round, then repeat the process, pouring less water into each child's vial, marking the water level with a small line using a fine felt marker (or coloured tape, etc.). Mark the parents' vials similarly with the water level. This will tell you how much sand to put into each vial at the start of the ceremony. If you've done it correctly, you will have exactly the right amount of sand. Test your measurements by pouring water into all the containers, up to the lines you marked. Transfer the water to the final vial, which should be full at the end of this process.
Now you're ready to do in on the wedding day with sand instead of water. Throroughly dry all vials and store them safely until the Day of Days. If you are using different colours of sand for each person (a good idea), then dry each vial, pour in sand up to your line, and store that sand with the vials, discarding any excess or saving it, separately wrapped, in reserve, as you prefer.
Good luck, and 'remmber nohting is prefect' ...
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The following is taken from an actual wedding I conducted for a blended family.
Will and Sue now wish to celebrate, not only their marriage today as a couple, but the blending of their lives with those of their children and grandchildren, by the mixing together of sand in this vial. It will be a permanent remembrance of how these people ~ husband, wife, children and grandchildren ~ have undertaken to unite as one blended family.
The foundation of this blending is the married couple themselves, as they lay a foundation for the future of their family.
(The couple pours the first layer - shake gently to level)
Each child will now add a new layer, each with their own coloured sand.
(Children pour their sand - shake gently to level)
And now, Will and Sue add the final layer, covering and protecting each member of the family with the love, the strength and the commitment of their marriage.
(Couple pours final layer - shake gently to level).
Will (hold separate sheet for Will to read):
Although our lives are joining and will be blended in many ways, each of us will remain a unique individual -- distinct from others. May this blending preserve the best qualities of each member of our family, and may every new day be one of discovery, as we all grow together in the love and knowledge of one another.
(The completed vial is sealed)