The quick answer is yes you can do that if you are using the terms exactly the way you are stating them. For a better understanding of why focus Items page Y278 explains it. Below is most of what is writen about your topic.
A single focus item slot, as granted by various Spellcraft powers (page 179), grants a +1 bonus. For evocation focuses, this bonus may be applied to either the wizard’s offensive power (Conviction) or offensive control (Discipline) or defensive power (Conviction) or defensive control (Discipline). For thaumaturgy focuses, this bonus may be applied to the wizard’s upper bound on “no-prep” complexity (Lore) for thaumaturgy or to the wizard’s control (Discipline) rolls for casting. The type of bonus must be determined and locked down at the time the item is created. In addition, you must specify which type of evocation or thaumaturgy is enhanced by the item’s bonus. An evocation focus is specified to work with a particular kind of element (e.g., fire, spirit). A thamaturgy focus is specified by any of the thaumaturgic types listed in this section, whether by function (e.g., summoning, veils, wards) or theme (e.g., biomancy, ectomancy, necromancy). Subsequent focus item slots allow you to create new focus items. Alternatively, one or more slots may be spent to add greater capacity to an existing focus item. The total number of slots a focus item uses is equal to the number of elements or types multiplied by the total of the bonuses. So an item that offered +1 offensive power and +1 offensive control to fire and earth evocations would take up 4 slots. All bonuses of an item always apply to all of the types on the item: you can’t have +2 complexity for necromancy and +1 complexity for wards in the same focus item, because the +2 complexity should apply to both necromancy and wards. This makes for narrow, potent focus items (one element or type with a large bonus) and broad, less potent focus items (many elements or types with a small bonus). Broad, potent focus items are very rare. As a result, most wizards tend to have many small bonus items for specific jobs, like a craftsman’s toolbox. The one restriction on the bonuses provided is that they may not total to a number greater than your Lore. So if your Lore is Good (+3), you can have an evocation focus item that provides +3 to offensive control, offensive power, defensive power, or defensive control, or a focus item that provides +1 to three of those, or +2 to one and +1 to another, but you can’t construct one that provides bonuses totaling 4 or more. The number of elements or types is not restricted, so long as you have enough slots to accommodate them. If you are willing to lock the item down to only ever being useful for one specific spell— such as an established evocation rote or a divination spell that always looks for the same thing—then you get a single free “slot upgrade” (as described below) to add an extra +1 bonus. You can’t benefit from the same type of bonus (e.g., a control bonus) from two or more items at the same time—so if you had two items, one with a +2 control bonus and another with a +1 control bonus, the total effect is a +2 to control.
Example: Evan Montrose has three focus
item slots. He could make a single wand that
takes up all three slots, giving him +3 offensive
power for wind evocation only, or he could split
the bonuses up, for +2 offensive power and
+1 offensive control. He could also make it
more multi-purpose, taking just a +1 offensive
power bonus, but applying it to wind, water,
and earth evocations.
